builtin: add libbacktrace as option for generating stack traces (#14277)

thirdparty/libbacktrace/amalgamation.txt

@@ -0,0 +1,4 @@
+The libbacktrace source is distributed here as an amalgamation (https://sqlite.org/amalgamation.html).
+This means that, rather than mirroring the entire libbacktrace repo here, most of the source code is
+packaged into one C file while other platform-specific code are into their respective C files which
+is much easier to handle.

thirdparty/libbacktrace/backtrace.c

@@ -0,0 +1,111 @@
+/* Copyright (C) 2012-2021 Free Software Foundation, Inc.
+   Written by Ian Lance Taylor, Google.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    (1) Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+    (2) Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in
+    the documentation and/or other materials provided with the
+    distribution.
+
+    (3) The name of the author may not be used to
+    endorse or promote products derived from this software without
+    specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.  */
+
+#define HAVE_ATOMIC_FUNCTIONS 1
+#define HAVE_CLOCK_GETTIME 1
+#define HAVE_DECL_GETPAGESIZE 0
+#define HAVE_DECL_STRNLEN 1
+#define HAVE_DL_ITERATE_PHDR 1
+#define HAVE_GETIPINFO 1
+#define HAVE_LSTAT 1
+#define HAVE_READLINK 1
+#define HAVE_SYNC_FUNCTIONS 1
+
+#define HAVE_DLFCN_H 1
+#define HAVE_INTTYPES_H 1
+#define HAVE_LINK_H 1
+#define HAVE_MEMORY_H 1
+#define HAVE_STDINT_H 1
+#define HAVE_STDLIB_H 1
+#define HAVE_STRINGS_H 1
+#define HAVE_STRING_H 1
+#define HAVE_UNISTD_H 1
+#define STDC_HEADERS 1
+#include <stdint.h>
+#if UINTPTR_MAX == 0xFFFFFFFF
+  #define BACKTRACE_ELF_SIZE 32
+  #define BACKTRACE_XCOFF_SIZE 32
+#elif UINTPTR_MAX == 0xFFFFFFFFFFFFFFFFu
+  #define BACKTRACE_ELF_SIZE 64
+  #define BACKTRACE_XCOFF_SIZE 64
+#endif
+#ifdef __TINYC__
+  #undef HAVE_ATOMIC_FUNCTIONS
+  #undef HAVE_SYNC_FUNCTIONS
+#endif
+#ifndef _WIN32
+#define HAVE_FCNTL 1
+#endif
+#if defined(__OpenBSD__) || defined(__FreeBSD__) || defined(__NetBSD__) || defined(__DragonFly__)
+  #define HAVE_KERN_PROC 1
+  #define HAVE_KERN_PROC_ARGS 1
+#endif
+#ifdef __APPLE__
+  #define HAVE_MACH_O_DYLD_H 1
+#endif
+#ifndef _ALL_SOURCE
+  #define _ALL_SOURCE 1
+#endif
+#ifndef _GNU_SOURCE
+  #define _GNU_SOURCE 1
+  #undef HAVE_DL_ITERATE_PHDR
+#endif
+#ifndef _POSIX_PTHREAD_SEMANTICS
+  #define _POSIX_PTHREAD_SEMANTICS 1
+#endif
+#ifndef _TANDEM_SOURCE
+  #define _TANDEM_SOURCE 1
+#endif
+#ifndef __EXTENSIONS__
+  #define __EXTENSIONS__ 1
+#endif
+#ifndef _DARWIN_USE_64_BIT_INODE
+  #define _DARWIN_USE_64_BIT_INODE 1
+#endif
+
+#define BACKTRACE_SUPPORTED 1
+#define BACKTRACE_USES_MALLOC 1
+#define BACKTRACE_SUPPORTS_THREADS 1
+#define BACKTRACE_SUPPORTS_DATA 0
+
+#if __TINYC__
+  #undef BACKTRACE_SUPPORTED
+#endif
+
+#include "base.c"
+
+#if defined(__linux__) || defined(__OpenBSD__) || defined(__FreeBSD__) || defined(__NetBSD__) || defined(__DragonFly__)
+  #include "linux.c"
+#elif defined(__APPLE__)
+  #include "darwin.c"
+#elif defined(_WIN32)
+  #include "windows.c"
+#endif

thirdparty/libbacktrace/backtrace.h

@@ -0,0 +1,189 @@
+/* backtrace.h -- Public header file for stack backtrace library.
+   Copyright (C) 2012-2021 Free Software Foundation, Inc.
+   Written by Ian Lance Taylor, Google.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    (1) Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+    (2) Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in
+    the documentation and/or other materials provided with the
+    distribution.
+
+    (3) The name of the author may not be used to
+    endorse or promote products derived from this software without
+    specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.  */
+
+#ifndef BACKTRACE_H
+#define BACKTRACE_H
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* The backtrace state.  This struct is intentionally not defined in
+   the public interface.  */
+
+struct backtrace_state;
+
+/* The type of the error callback argument to backtrace functions.
+   This function, if not NULL, will be called for certain error cases.
+   The DATA argument is passed to the function that calls this one.
+   The MSG argument is an error message.  The ERRNUM argument, if
+   greater than 0, holds an errno value.  The MSG buffer may become
+   invalid after this function returns.
+
+   As a special case, the ERRNUM argument will be passed as -1 if no
+   debug info can be found for the executable, or if the debug info
+   exists but has an unsupported version, but the function requires
+   debug info (e.g., backtrace_full, backtrace_pcinfo).  The MSG in
+   this case will be something along the lines of "no debug info".
+   Similarly, ERRNUM will be passed as -1 if there is no symbol table,
+   but the function requires a symbol table (e.g., backtrace_syminfo).
+   This may be used as a signal that some other approach should be
+   tried.  */
+
+typedef void (*backtrace_error_callback) (void *data, const char *msg,
+					  int errnum);
+
+/* Create state information for the backtrace routines.  This must be
+   called before any of the other routines, and its return value must
+   be passed to all of the other routines.  FILENAME is the path name
+   of the executable file; if it is NULL the library will try
+   system-specific path names.  If not NULL, FILENAME must point to a
+   permanent buffer.  If THREADED is non-zero the state may be
+   accessed by multiple threads simultaneously, and the library will
+   use appropriate atomic operations.  If THREADED is zero the state
+   may only be accessed by one thread at a time.  This returns a state
+   pointer on success, NULL on error.  If an error occurs, this will
+   call the ERROR_CALLBACK routine.
+
+   Calling this function allocates resources that cannot be freed.
+   There is no backtrace_free_state function.  The state is used to
+   cache information that is expensive to recompute.  Programs are
+   expected to call this function at most once and to save the return
+   value for all later calls to backtrace functions.  */
+
+extern struct backtrace_state *backtrace_create_state (
+    const char *filename, int threaded,
+    backtrace_error_callback error_callback, void *data);
+
+/* The type of the callback argument to the backtrace_full function.
+   DATA is the argument passed to backtrace_full.  PC is the program
+   counter.  FILENAME is the name of the file containing PC, or NULL
+   if not available.  LINENO is the line number in FILENAME containing
+   PC, or 0 if not available.  FUNCTION is the name of the function
+   containing PC, or NULL if not available.  This should return 0 to
+   continuing tracing.  The FILENAME and FUNCTION buffers may become
+   invalid after this function returns.  */
+
+typedef int (*backtrace_full_callback) (void *data, uintptr_t pc,
+					const char *filename, int lineno,
+					const char *function);
+
+/* Get a full stack backtrace.  SKIP is the number of frames to skip;
+   passing 0 will start the trace with the function calling
+   backtrace_full.  DATA is passed to the callback routine.  If any
+   call to CALLBACK returns a non-zero value, the stack backtrace
+   stops, and backtrace returns that value; this may be used to limit
+   the number of stack frames desired.  If all calls to CALLBACK
+   return 0, backtrace returns 0.  The backtrace_full function will
+   make at least one call to either CALLBACK or ERROR_CALLBACK.  This
+   function requires debug info for the executable.  */
+
+extern int backtrace_full (struct backtrace_state *state, int skip,
+			   backtrace_full_callback callback,
+			   backtrace_error_callback error_callback,
+			   void *data);
+
+/* The type of the callback argument to the backtrace_simple function.
+   DATA is the argument passed to simple_backtrace.  PC is the program
+   counter.  This should return 0 to continue tracing.  */
+
+typedef int (*backtrace_simple_callback) (void *data, uintptr_t pc);
+
+/* Get a simple backtrace.  SKIP is the number of frames to skip, as
+   in backtrace.  DATA is passed to the callback routine.  If any call
+   to CALLBACK returns a non-zero value, the stack backtrace stops,
+   and backtrace_simple returns that value.  Otherwise
+   backtrace_simple returns 0.  The backtrace_simple function will
+   make at least one call to either CALLBACK or ERROR_CALLBACK.  This
+   function does not require any debug info for the executable.  */
+
+extern int backtrace_simple (struct backtrace_state *state, int skip,
+			     backtrace_simple_callback callback,
+			     backtrace_error_callback error_callback,
+			     void *data);
+
+/* Print the current backtrace in a user readable format to a FILE.
+   SKIP is the number of frames to skip, as in backtrace_full.  Any
+   error messages are printed to stderr.  This function requires debug
+   info for the executable.  */
+
+extern void backtrace_print (struct backtrace_state *state, int skip, FILE *);
+
+/* Given PC, a program counter in the current program, call the
+   callback function with filename, line number, and function name
+   information.  This will normally call the callback function exactly
+   once.  However, if the PC happens to describe an inlined call, and
+   the debugging information contains the necessary information, then
+   this may call the callback function multiple times.  This will make
+   at least one call to either CALLBACK or ERROR_CALLBACK.  This
+   returns the first non-zero value returned by CALLBACK, or 0.  */
+
+extern int backtrace_pcinfo (struct backtrace_state *state, uintptr_t pc,
+			     backtrace_full_callback callback,
+			     backtrace_error_callback error_callback,
+			     void *data);
+
+/* The type of the callback argument to backtrace_syminfo.  DATA and
+   PC are the arguments passed to backtrace_syminfo.  SYMNAME is the
+   name of the symbol for the corresponding code.  SYMVAL is the
+   value and SYMSIZE is the size of the symbol.  SYMNAME will be NULL
+   if no error occurred but the symbol could not be found.  */
+
+typedef void (*backtrace_syminfo_callback) (void *data, uintptr_t pc,
+					    const char *symname,
+					    uintptr_t symval,
+					    uintptr_t symsize);
+
+/* Given ADDR, an address or program counter in the current program,
+   call the callback information with the symbol name and value
+   describing the function or variable in which ADDR may be found.
+   This will call either CALLBACK or ERROR_CALLBACK exactly once.
+   This returns 1 on success, 0 on failure.  This function requires
+   the symbol table but does not require the debug info.  Note that if
+   the symbol table is present but ADDR could not be found in the
+   table, CALLBACK will be called with a NULL SYMNAME argument.
+   Returns 1 on success, 0 on error.  */
+
+extern int backtrace_syminfo (struct backtrace_state *state, uintptr_t addr,
+			      backtrace_syminfo_callback callback,
+			      backtrace_error_callback error_callback,
+			      void *data);
+
+#ifdef __cplusplus
+} /* End extern "C".  */
+#endif
+
+#endif

thirdparty/libbacktrace/windows.c

@@ -0,0 +1,818 @@
+// pecoff.c:
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+
+typedef struct {
+  uint16_t machine;
+  uint16_t number_of_sections;
+  uint32_t time_date_stamp;
+  uint32_t pointer_to_symbol_table;
+  uint32_t number_of_symbols;
+  uint16_t size_of_optional_header;
+  uint16_t characteristics;
+} b_coff_file_header;
+
+typedef struct {
+  uint16_t magic;
+  uint8_t major_linker_version;
+  uint8_t minor_linker_version;
+  uint32_t size_of_code;
+  uint32_t size_of_initialized_data;
+  uint32_t size_of_uninitialized_data;
+  uint32_t address_of_entry_point;
+  uint32_t base_of_code;
+  union {
+    struct {
+      uint32_t base_of_data;
+      uint32_t image_base;
+    } pe;
+    struct {
+      uint64_t image_base;
+    } pep;
+  } u;
+} b_coff_optional_header;
+
+#define PE_MAGIC 0x10b
+#define PEP_MAGIC 0x20b
+
+typedef struct {
+  char name[8];
+  uint32_t virtual_size;
+  uint32_t virtual_address;
+  uint32_t size_of_raw_data;
+  uint32_t pointer_to_raw_data;
+  uint32_t pointer_to_relocations;
+  uint32_t pointer_to_line_numbers;
+  uint16_t number_of_relocations;
+  uint16_t number_of_line_numbers;
+  uint32_t characteristics;
+} b_coff_section_header;
+
+typedef union {
+  char short_name[8];
+  struct {
+    unsigned char zeroes[4];
+    unsigned char off[4];
+  } long_name;
+} b_coff_name;
+
+typedef struct {
+  b_coff_name name;
+  unsigned char value[4];
+  unsigned char section_number[2];
+  unsigned char type[2];
+  unsigned char storage_class;
+  unsigned char number_of_aux_symbols;
+} b_coff_external_symbol;
+
+#define N_TBSHFT 4
+#define IMAGE_SYM_DTYPE_FUNCTION 2
+
+#define SYM_SZ 18
+
+typedef struct {
+  const char *name;
+  uint32_t value;
+  int16_t sec;
+  uint16_t type;
+  uint16_t sc;
+} b_coff_internal_symbol;
+
+static const char *const debug_section_names[DEBUG_MAX] = {
+    ".debug_info",        ".debug_line",     ".debug_abbrev",
+    ".debug_ranges",      ".debug_str",      ".debug_addr",
+    ".debug_str_offsets", ".debug_line_str", ".debug_rnglists"};
+
+struct debug_section_info {
+  off_t offset;
+
+  size_t size;
+};
+
+struct coff_symbol {
+  const char *name;
+
+  uintptr_t address;
+};
+
+struct coff_syminfo_data {
+  struct coff_syminfo_data *next;
+
+  struct coff_symbol *symbols;
+
+  size_t count;
+};
+
+static int coff_nodebug(struct backtrace_state *state ATTRIBUTE_UNUSED,
+                        uintptr_t pc ATTRIBUTE_UNUSED,
+                        backtrace_full_callback callback ATTRIBUTE_UNUSED,
+                        backtrace_error_callback error_callback, void *data) {
+  error_callback(data, "no debug info in PE/COFF executable", -1);
+  return 0;
+}
+
+static void coff_nosyms(struct backtrace_state *state ATTRIBUTE_UNUSED,
+                        uintptr_t addr ATTRIBUTE_UNUSED,
+                        backtrace_syminfo_callback callback ATTRIBUTE_UNUSED,
+                        backtrace_error_callback error_callback, void *data) {
+  error_callback(data, "no symbol table in PE/COFF executable", -1);
+}
+
+static uint32_t coff_read4(const unsigned char *p) {
+  uint32_t res;
+
+  memcpy(&res, p, 4);
+  return res;
+}
+
+static uint16_t coff_read2(const unsigned char *p) {
+  uint16_t res;
+
+  memcpy(&res, p, sizeof(res));
+  return res;
+}
+
+static size_t coff_short_name_len(const char *name) {
+  int i;
+
+  for (i = 0; i < 8; i++)
+    if (name[i] == 0) return i;
+  return 8;
+}
+
+static int coff_short_name_eq(const char *name, const char *cname) {
+  int i;
+
+  for (i = 0; i < 8; i++) {
+    if (name[i] != cname[i]) return 0;
+    if (name[i] == 0) return 1;
+  }
+  return name[8] == 0;
+}
+
+static int coff_long_name_eq(const char *name, unsigned int off,
+                             struct backtrace_view *str_view) {
+  if (off >= str_view->len) return 0;
+  return strcmp(name, (const char *)str_view->data + off) == 0;
+}
+
+static int coff_symbol_compare(const void *v1, const void *v2) {
+  const struct coff_symbol *e1 = (const struct coff_symbol *)v1;
+  const struct coff_symbol *e2 = (const struct coff_symbol *)v2;
+
+  if (e1->address < e2->address)
+    return -1;
+  else if (e1->address > e2->address)
+    return 1;
+  else
+    return 0;
+}
+
+static int coff_expand_symbol(b_coff_internal_symbol *isym,
+                              const b_coff_external_symbol *sym,
+                              uint16_t sects_num, const unsigned char *strtab,
+                              size_t strtab_size) {
+  isym->type = coff_read2(sym->type);
+  isym->sec = coff_read2(sym->section_number);
+  isym->sc = sym->storage_class;
+
+  if (isym->sec > 0 && (uint16_t)isym->sec > sects_num) return -1;
+  if (sym->name.short_name[0] != 0)
+    isym->name = sym->name.short_name;
+  else {
+    uint32_t off = coff_read4(sym->name.long_name.off);
+
+    if (off >= strtab_size) return -1;
+    isym->name = (const char *)strtab + off;
+  }
+  return 0;
+}
+
+static int coff_is_function_symbol(const b_coff_internal_symbol *isym) {
+  return (isym->type >> N_TBSHFT) == IMAGE_SYM_DTYPE_FUNCTION && isym->sec > 0;
+}
+
+static int coff_initialize_syminfo(
+    struct backtrace_state *state, uintptr_t base_address, int is_64,
+    const b_coff_section_header *sects, size_t sects_num,
+    const b_coff_external_symbol *syms, size_t syms_size,
+    const unsigned char *strtab, size_t strtab_size,
+    backtrace_error_callback error_callback, void *data,
+    struct coff_syminfo_data *sdata) {
+  size_t syms_count;
+  char *coff_symstr;
+  size_t coff_symstr_len;
+  size_t coff_symbol_count;
+  size_t coff_symbol_size;
+  struct coff_symbol *coff_symbols;
+  struct coff_symbol *coff_sym;
+  char *coff_str;
+  size_t i;
+
+  syms_count = syms_size / SYM_SZ;
+
+  coff_symbol_count = 0;
+  coff_symstr_len = 0;
+  for (i = 0; i < syms_count; ++i) {
+    const b_coff_external_symbol *asym = &syms[i];
+    b_coff_internal_symbol isym;
+
+    if (coff_expand_symbol(&isym, asym, sects_num, strtab, strtab_size) < 0) {
+      error_callback(data, "invalid section or offset in coff symbol", 0);
+      return 0;
+    }
+    if (coff_is_function_symbol(&isym)) {
+      ++coff_symbol_count;
+      if (asym->name.short_name[0] != 0)
+        coff_symstr_len += coff_short_name_len(asym->name.short_name) + 1;
+    }
+
+    i += asym->number_of_aux_symbols;
+  }
+
+  coff_symbol_size = (coff_symbol_count + 1) * sizeof(struct coff_symbol);
+  coff_symbols = ((struct coff_symbol *)backtrace_alloc(state, coff_symbol_size,
+                                                        error_callback, data));
+  if (coff_symbols == NULL) return 0;
+
+  if (coff_symstr_len > 0) {
+    coff_symstr =
+        ((char *)backtrace_alloc(state, coff_symstr_len, error_callback, data));
+    if (coff_symstr == NULL) {
+      backtrace_free(state, coff_symbols, coff_symbol_size, error_callback,
+                     data);
+      return 0;
+    }
+  } else
+    coff_symstr = NULL;
+
+  coff_sym = coff_symbols;
+  coff_str = coff_symstr;
+  for (i = 0; i < syms_count; ++i) {
+    const b_coff_external_symbol *asym = &syms[i];
+    b_coff_internal_symbol isym;
+
+    if (coff_expand_symbol(&isym, asym, sects_num, strtab, strtab_size)) {
+      abort();
+    }
+    if (coff_is_function_symbol(&isym)) {
+      const char *name;
+      int16_t secnum;
+
+      if (asym->name.short_name[0] != 0) {
+        size_t len = coff_short_name_len(isym.name);
+        name = coff_str;
+        memcpy(coff_str, isym.name, len);
+        coff_str[len] = 0;
+        coff_str += len + 1;
+      } else
+        name = isym.name;
+
+      if (!is_64) {
+        if (name[0] == '_') name++;
+      }
+
+      secnum = coff_read2(asym->section_number);
+
+      coff_sym->name = name;
+      coff_sym->address = (coff_read4(asym->value) +
+                           sects[secnum - 1].virtual_address + base_address);
+      coff_sym++;
+    }
+
+    i += asym->number_of_aux_symbols;
+  }
+
+  coff_sym->name = NULL;
+  coff_sym->address = -1;
+
+  backtrace_qsort(coff_symbols, coff_symbol_count, sizeof(struct coff_symbol),
+                  coff_symbol_compare);
+
+  sdata->next = NULL;
+  sdata->symbols = coff_symbols;
+  sdata->count = coff_symbol_count;
+
+  return 1;
+}
+
+static void coff_add_syminfo_data(struct backtrace_state *state,
+                                  struct coff_syminfo_data *sdata) {
+  if (!state->threaded) {
+    struct coff_syminfo_data **pp;
+
+    for (pp = (struct coff_syminfo_data **)(void *)&state->syminfo_data;
+         *pp != NULL; pp = &(*pp)->next)
+      ;
+    *pp = sdata;
+  } else {
+    while (1) {
+      struct coff_syminfo_data **pp;
+
+      pp = (struct coff_syminfo_data **)(void *)&state->syminfo_data;
+
+      while (1) {
+        struct coff_syminfo_data *p;
+
+        p = backtrace_atomic_load_pointer(pp);
+
+        if (p == NULL) break;
+
+        pp = &p->next;
+      }
+
+      if (__sync_bool_compare_and_swap(pp, NULL, sdata)) break;
+    }
+  }
+}
+
+static int coff_symbol_search(const void *vkey, const void *ventry) {
+  const uintptr_t *key = (const uintptr_t *)vkey;
+  const struct coff_symbol *entry = (const struct coff_symbol *)ventry;
+  uintptr_t addr;
+
+  addr = *key;
+  if (addr < entry->address)
+    return -1;
+  else if (addr >= entry[1].address)
+    return 1;
+  else
+    return 0;
+}
+
+static void coff_syminfo(
+    struct backtrace_state *state, uintptr_t addr,
+    backtrace_syminfo_callback callback,
+    backtrace_error_callback error_callback ATTRIBUTE_UNUSED, void *data) {
+  struct coff_syminfo_data *sdata;
+  struct coff_symbol *sym = NULL;
+
+  if (!state->threaded) {
+    for (sdata = (struct coff_syminfo_data *)state->syminfo_data; sdata != NULL;
+         sdata = sdata->next) {
+      sym = ((struct coff_symbol *)bsearch(&addr, sdata->symbols, sdata->count,
+                                           sizeof(struct coff_symbol),
+                                           coff_symbol_search));
+      if (sym != NULL) break;
+    }
+  } else {
+    struct coff_syminfo_data **pp;
+
+    pp = (struct coff_syminfo_data **)(void *)&state->syminfo_data;
+    while (1) {
+      sdata = backtrace_atomic_load_pointer(pp);
+      if (sdata == NULL) break;
+
+      sym = ((struct coff_symbol *)bsearch(&addr, sdata->symbols, sdata->count,
+                                           sizeof(struct coff_symbol),
+                                           coff_symbol_search));
+      if (sym != NULL) break;
+
+      pp = &sdata->next;
+    }
+  }
+
+  if (sym == NULL)
+    callback(data, addr, NULL, 0, 0);
+  else
+    callback(data, addr, sym->name, sym->address, 0);
+}
+
+static int coff_add(struct backtrace_state *state, int descriptor,
+                    backtrace_error_callback error_callback, void *data,
+                    fileline *fileline_fn, int *found_sym, int *found_dwarf) {
+  struct backtrace_view fhdr_view;
+  off_t fhdr_off;
+  int magic_ok;
+  b_coff_file_header fhdr;
+  off_t opt_sects_off;
+  size_t opt_sects_size;
+  unsigned int sects_num;
+  struct backtrace_view sects_view;
+  int sects_view_valid;
+  const b_coff_optional_header *opt_hdr;
+  const b_coff_section_header *sects;
+  struct backtrace_view str_view;
+  int str_view_valid;
+  size_t str_size;
+  off_t str_off;
+  struct backtrace_view syms_view;
+  off_t syms_off;
+  size_t syms_size;
+  int syms_view_valid;
+  unsigned int syms_num;
+  unsigned int i;
+  struct debug_section_info sections[DEBUG_MAX];
+  off_t min_offset;
+  off_t max_offset;
+  struct backtrace_view debug_view;
+  int debug_view_valid;
+  int is_64;
+  uintptr_t image_base;
+  struct dwarf_sections dwarf_sections;
+
+  *found_sym = 0;
+  *found_dwarf = 0;
+
+  sects_view_valid = 0;
+  syms_view_valid = 0;
+  str_view_valid = 0;
+  debug_view_valid = 0;
+
+  if (!backtrace_get_view(state, descriptor, 0, 0x40, error_callback, data,
+                          &fhdr_view))
+    goto fail;
+
+  {
+    const unsigned char *vptr = fhdr_view.data;
+
+    if (vptr[0] == 'M' && vptr[1] == 'Z')
+      fhdr_off = coff_read4(vptr + 0x3c);
+    else
+      fhdr_off = 0;
+  }
+
+  backtrace_release_view(state, &fhdr_view, error_callback, data);
+
+  if (!backtrace_get_view(state, descriptor, fhdr_off,
+                          sizeof(b_coff_file_header) + 4, error_callback, data,
+                          &fhdr_view))
+    goto fail;
+
+  if (fhdr_off != 0) {
+    const char *magic = (const char *)fhdr_view.data;
+    magic_ok = memcmp(magic, "PE\0", 4) == 0;
+    fhdr_off += 4;
+
+    memcpy(&fhdr, fhdr_view.data + 4, sizeof fhdr);
+  } else {
+    memcpy(&fhdr, fhdr_view.data, sizeof fhdr);
+
+    magic_ok = 0;
+  }
+  backtrace_release_view(state, &fhdr_view, error_callback, data);
+
+  if (!magic_ok) {
+    error_callback(data, "executable file is not COFF", 0);
+    goto fail;
+  }
+
+  sects_num = fhdr.number_of_sections;
+  syms_num = fhdr.number_of_symbols;
+
+  opt_sects_off = fhdr_off + sizeof(fhdr);
+  opt_sects_size = (fhdr.size_of_optional_header +
+                    sects_num * sizeof(b_coff_section_header));
+
+  if (!backtrace_get_view(state, descriptor, opt_sects_off, opt_sects_size,
+                          error_callback, data, &sects_view))
+    goto fail;
+  sects_view_valid = 1;
+  opt_hdr = (const b_coff_optional_header *)sects_view.data;
+  sects = (const b_coff_section_header *)(sects_view.data +
+                                          fhdr.size_of_optional_header);
+
+  is_64 = 0;
+  if (fhdr.size_of_optional_header > sizeof(*opt_hdr)) {
+    if (opt_hdr->magic == PE_MAGIC)
+      image_base = opt_hdr->u.pe.image_base;
+    else if (opt_hdr->magic == PEP_MAGIC) {
+      image_base = opt_hdr->u.pep.image_base;
+      is_64 = 1;
+    } else {
+      error_callback(data, "bad magic in PE optional header", 0);
+      goto fail;
+    }
+  } else
+    image_base = 0;
+
+  if (fhdr.pointer_to_symbol_table == 0) {
+    str_off = 0;
+    str_size = 0;
+    syms_num = 0;
+    syms_size = 0;
+  } else {
+    syms_off = fhdr.pointer_to_symbol_table;
+    syms_size = syms_num * SYM_SZ;
+
+    if (!backtrace_get_view(state, descriptor, syms_off, syms_size + 4,
+                            error_callback, data, &syms_view))
+      goto fail;
+    syms_view_valid = 1;
+
+    str_size = coff_read4(syms_view.data + syms_size);
+
+    str_off = syms_off + syms_size;
+
+    if (str_size > 4) {
+      if (!backtrace_get_view(state, descriptor, str_off, str_size,
+                              error_callback, data, &str_view))
+        goto fail;
+      str_view_valid = 1;
+    }
+  }
+
+  memset(sections, 0, sizeof sections);
+
+  for (i = 0; i < sects_num; ++i) {
+    const b_coff_section_header *s = sects + i;
+    unsigned int str_off;
+    int j;
+
+    if (s->name[0] == '/') {
+      str_off = atoi(s->name + 1);
+    } else
+      str_off = 0;
+
+    for (j = 0; j < (int)DEBUG_MAX; ++j) {
+      const char *dbg_name = debug_section_names[j];
+      int match;
+
+      if (str_off != 0)
+        match = coff_long_name_eq(dbg_name, str_off, &str_view);
+      else
+        match = coff_short_name_eq(dbg_name, s->name);
+      if (match) {
+        sections[j].offset = s->pointer_to_raw_data;
+        sections[j].size = s->virtual_size <= s->size_of_raw_data
+                               ? s->virtual_size
+                               : s->size_of_raw_data;
+        break;
+      }
+    }
+  }
+
+  if (syms_num != 0) {
+    struct coff_syminfo_data *sdata;
+
+    sdata = ((struct coff_syminfo_data *)backtrace_alloc(state, sizeof *sdata,
+                                                         error_callback, data));
+    if (sdata == NULL) goto fail;
+
+    if (!coff_initialize_syminfo(state, image_base, is_64, sects, sects_num,
+                                 syms_view.data, syms_size, str_view.data,
+                                 str_size, error_callback, data, sdata)) {
+      backtrace_free(state, sdata, sizeof *sdata, error_callback, data);
+      goto fail;
+    }
+
+    *found_sym = 1;
+
+    coff_add_syminfo_data(state, sdata);
+  }
+
+  backtrace_release_view(state, &sects_view, error_callback, data);
+  sects_view_valid = 0;
+  if (syms_view_valid) {
+    backtrace_release_view(state, &syms_view, error_callback, data);
+    syms_view_valid = 0;
+  }
+
+  min_offset = 0;
+  max_offset = 0;
+  for (i = 0; i < (int)DEBUG_MAX; ++i) {
+    off_t end;
+
+    if (sections[i].size == 0) continue;
+    if (min_offset == 0 || sections[i].offset < min_offset)
+      min_offset = sections[i].offset;
+    end = sections[i].offset + sections[i].size;
+    if (end > max_offset) max_offset = end;
+  }
+  if (min_offset == 0 || max_offset == 0) {
+    if (!backtrace_close(descriptor, error_callback, data)) goto fail;
+    *fileline_fn = coff_nodebug;
+    return 1;
+  }
+
+  if (!backtrace_get_view(state, descriptor, min_offset,
+                          max_offset - min_offset, error_callback, data,
+                          &debug_view))
+    goto fail;
+  debug_view_valid = 1;
+
+  if (!backtrace_close(descriptor, error_callback, data)) goto fail;
+  descriptor = -1;
+
+  for (i = 0; i < (int)DEBUG_MAX; ++i) {
+    size_t size = sections[i].size;
+    dwarf_sections.size[i] = size;
+    if (size == 0)
+      dwarf_sections.data[i] = NULL;
+    else
+      dwarf_sections.data[i] = ((const unsigned char *)debug_view.data +
+                                (sections[i].offset - min_offset));
+  }
+
+  if (!backtrace_dwarf_add(state, 0, &dwarf_sections, 0, NULL, error_callback,
+                           data, fileline_fn, NULL))
+    goto fail;
+
+  *found_dwarf = 1;
+
+  return 1;
+
+fail:
+  if (sects_view_valid)
+    backtrace_release_view(state, &sects_view, error_callback, data);
+  if (str_view_valid)
+    backtrace_release_view(state, &str_view, error_callback, data);
+  if (syms_view_valid)
+    backtrace_release_view(state, &syms_view, error_callback, data);
+  if (debug_view_valid)
+    backtrace_release_view(state, &debug_view, error_callback, data);
+  if (descriptor != -1) backtrace_close(descriptor, error_callback, data);
+  return 0;
+}
+
+int backtrace_initialize(struct backtrace_state *state,
+                         const char *filename ATTRIBUTE_UNUSED, int descriptor,
+                         backtrace_error_callback error_callback, void *data,
+                         fileline *fileline_fn) {
+  int ret;
+  int found_sym;
+  int found_dwarf;
+  fileline coff_fileline_fn;
+
+  ret = coff_add(state, descriptor, error_callback, data, &coff_fileline_fn,
+                 &found_sym, &found_dwarf);
+  if (!ret) return 0;
+
+  if (!state->threaded) {
+    if (found_sym)
+      state->syminfo_fn = coff_syminfo;
+    else if (state->syminfo_fn == NULL)
+      state->syminfo_fn = coff_nosyms;
+  } else {
+    if (found_sym)
+      backtrace_atomic_store_pointer(&state->syminfo_fn, coff_syminfo);
+    else
+      (void)__sync_bool_compare_and_swap(&state->syminfo_fn, NULL, coff_nosyms);
+  }
+
+  if (!state->threaded) {
+    if (state->fileline_fn == NULL || state->fileline_fn == coff_nodebug)
+      *fileline_fn = coff_fileline_fn;
+  } else {
+    fileline current_fn;
+
+    current_fn = backtrace_atomic_load_pointer(&state->fileline_fn);
+    if (current_fn == NULL || current_fn == coff_nodebug)
+      *fileline_fn = coff_fileline_fn;
+  }
+
+  return 1;
+}
+
+// read.c:
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+int backtrace_get_view(struct backtrace_state *state, int descriptor,
+                       off_t offset, uint64_t size,
+                       backtrace_error_callback error_callback, void *data,
+                       struct backtrace_view *view) {
+  uint64_t got;
+  ssize_t r;
+
+  if ((uint64_t)(size_t)size != size) {
+    error_callback(data, "file size too large", 0);
+    return 0;
+  }
+
+  if (lseek(descriptor, offset, SEEK_SET) < 0) {
+    error_callback(data, "lseek", errno);
+    return 0;
+  }
+
+  view->base = backtrace_alloc(state, size, error_callback, data);
+  if (view->base == NULL) return 0;
+  view->data = view->base;
+  view->len = size;
+
+  got = 0;
+  while (got < size) {
+    r = read(descriptor, view->base, size - got);
+    if (r < 0) {
+      error_callback(data, "read", errno);
+      free(view->base);
+      return 0;
+    }
+    if (r == 0) break;
+    got += (uint64_t)r;
+  }
+
+  if (got < size) {
+    error_callback(data, "file too short", 0);
+    free(view->base);
+    return 0;
+  }
+
+  return 1;
+}
+
+void backtrace_release_view(struct backtrace_state *state,
+                            struct backtrace_view *view,
+                            backtrace_error_callback error_callback,
+                            void *data) {
+  backtrace_free(state, view->base, view->len, error_callback, data);
+  view->data = NULL;
+  view->base = NULL;
+}
+
+// alloc.c:
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/types.h>
+
+void *backtrace_alloc(struct backtrace_state *state ATTRIBUTE_UNUSED,
+                      size_t size, backtrace_error_callback error_callback,
+                      void *data) {
+  void *ret;
+
+  ret = malloc(size);
+  if (ret == NULL) {
+    if (error_callback) error_callback(data, "malloc", errno);
+  }
+  return ret;
+}
+
+void backtrace_free(struct backtrace_state *state ATTRIBUTE_UNUSED, void *p,
+                    size_t size ATTRIBUTE_UNUSED,
+                    backtrace_error_callback error_callback ATTRIBUTE_UNUSED,
+                    void *data ATTRIBUTE_UNUSED) {
+  free(p);
+}
+
+void *backtrace_vector_grow(struct backtrace_state *state ATTRIBUTE_UNUSED,
+                            size_t size,
+                            backtrace_error_callback error_callback, void *data,
+                            struct backtrace_vector *vec) {
+  void *ret;
+
+  if (size > vec->alc) {
+    size_t alc;
+    void *base;
+
+    if (vec->size == 0)
+      alc = 32 * size;
+    else if (vec->size >= 4096)
+      alc = vec->size + 4096;
+    else
+      alc = 2 * vec->size;
+
+    if (alc < vec->size + size) alc = vec->size + size;
+
+    base = realloc(vec->base, alc);
+    if (base == NULL) {
+      error_callback(data, "realloc", errno);
+      return NULL;
+    }
+
+    vec->base = base;
+    vec->alc = alc - vec->size;
+  }
+
+  ret = (char *)vec->base + vec->size;
+  vec->size += size;
+  vec->alc -= size;
+  return ret;
+}
+
+void *backtrace_vector_finish(struct backtrace_state *state,
+                              struct backtrace_vector *vec,
+                              backtrace_error_callback error_callback,
+                              void *data) {
+  void *ret;
+
+  if (!backtrace_vector_release(state, vec, error_callback, data)) return NULL;
+  ret = vec->base;
+  vec->base = NULL;
+  vec->size = 0;
+  vec->alc = 0;
+  return ret;
+}
+
+int backtrace_vector_release(struct backtrace_state *state ATTRIBUTE_UNUSED,
+                             struct backtrace_vector *vec,
+                             backtrace_error_callback error_callback,
+                             void *data) {
+  vec->alc = 0;
+
+  if (vec->size == 0) {
+    free(vec->base);
+    vec->base = NULL;
+    return 1;
+  }
+
+  vec->base = realloc(vec->base, vec->size);
+  if (vec->base == NULL) {
+    error_callback(data, "realloc", errno);
+    return 0;
+  }
+
+  return 1;
+}

vlib/builtin/builtin.c.v

@@ -54,7 +54,11 @@ fn panic_debug(line_no int, file string, mod string, fn_name string, s string) {
 				}
 				C.exit(1)
 			}
+			$if use_libbacktrace ? {
+				print_libbacktrace(1)
+			} $else {
 				print_backtrace_skipping_top_frames(1)
+			}
 			$if panics_break_into_debugger ? {
 				break_if_debugger_attached()
 			}
@@ -101,7 +105,11 @@ pub fn panic(s string) {
 				}
 				C.exit(1)
 			}
+			$if use_libbacktrace ? {
+				print_libbacktrace(1)
+			} $else {
 				print_backtrace_skipping_top_frames(1)
+			}
 			$if panics_break_into_debugger ? {
 				break_if_debugger_attached()
 			}
@@ -556,9 +564,24 @@ pub fn print_backtrace() {
 		} $else {
 			$if tinyc {
 				C.tcc_backtrace(c'Backtrace')
+			} $else {
+				// NOTE: TCC doesn't have the unwind library
+				$if use_libbacktrace ? {
+					print_libbacktrace(1)
 				} $else {
 					print_backtrace_skipping_top_frames(2)
 				}
 			}
 		}
+	}
 }
+
+// NOTE: g_main_argc and g_main_argv are filled in right after C's main start.
+// They are used internally by V's builtin; for user code, it is much
+// more convenient to just use `os.args` instead.
+
+[markused]
+__global g_main_argc = int(0)
+
+[markused]
+__global g_main_argv = voidptr(0)

vlib/builtin/builtin_d_use_libbacktrace.c.v

@@ -0,0 +1,86 @@
+[has_globals]
+module builtin
+
+#flag -I@VEXEROOT/thirdparty/libbacktrace
+#flag @VEXEROOT/thirdparty/libbacktrace/backtrace.o
+#include <backtrace.h>
+
+// NOTE: Don't mark this as a [typedef] or it may cause compiler errors!
+struct C.backtrace_state {
+	// filename &char
+}
+
+type BacktraceErrorCallback = fn (data voidptr, msg &char, errnum int) voidptr
+
+type BacktraceFullCallback = fn (data voidptr, pc voidptr, filename &char, lineno int, func &char) &int
+
+fn C.backtrace_create_state(filename &char, threaded int, error_callback BacktraceErrorCallback, data voidptr) &C.backtrace_state
+fn C.backtrace_full(state &C.backtrace_state, skip int, cb BacktraceFullCallback, err_cb BacktraceErrorCallback, data voidptr) int
+
+__global bt_state = init_bt_state()
+
+fn init_bt_state() &C.backtrace_state {
+	$if !tinyc {
+		mut filename := &char(0)
+		$if windows {
+			filename = unsafe { string_from_wide(&&u16(g_main_argv)[0]).str }
+		} $else {
+			filename = unsafe { &&char(g_main_argv)[0] }
+		}
+		return C.backtrace_create_state(filename, 1, bt_error_handler, 0)
+	}
+	return &C.backtrace_state(0)
+}
+
+// for bt_error_callback
+// struct BacktraceData {
+// 	state &C.backtrace_state
+// }
+
+fn bt_print_callback(data voidptr, pc voidptr, filename_ptr &char, line int, fn_name_ptr &char) int {
+	filename := if isnil(filename_ptr) { '???' } else { unsafe { filename_ptr.vstring() } }
+	fn_name := if isnil(fn_name_ptr) {
+		'???'
+	} else {
+		(unsafe { fn_name_ptr.vstring() }).replace('__', '.')
+	}
+	// keep it for later
+	// pc_64 := u64(pc)
+	println('$filename:$line: by $fn_name')
+	return 0
+}
+
+fn bt_error_callback(data voidptr, msg_ptr &char, errnum int) {
+	// if !isnil(data) && !isnil(data.state) && !isnil(data.state.filename) {
+	// 	filename := unsafe{ data.state.filename.vstring() }
+	// 	eprint('$filename: ')
+	// }
+
+	msg := unsafe { msg_ptr.vstring() }
+	eprint('libbacktrace: $msg')
+	if errnum > 0 {
+		eprint(': ${C.strerror(errnum)}')
+	}
+
+	eprintln('')
+}
+
+// for backtrace_create_state only
+fn bt_error_handler(data voidptr, msg &char, errnum int) {
+	eprint('libbacktrace: ')
+	eprint(unsafe { msg.vstring() })
+	if errnum > 0 {
+		eprint(': ${C.strerror(errnum)}')
+	}
+	eprintln('')
+	exit(1)
+}
+
+[noinline]
+fn print_libbacktrace(frames_to_skip int) {
+	$if no_backtrace ? {
+		return
+	}
+	// data := &BacktraceData{bt_state}
+	C.backtrace_full(bt_state, frames_to_skip, bt_print_callback, bt_error_callback, 0)
+}

vlib/builtin/builtin_notd_use_libbacktrace.c.v

@@ -0,0 +1,4 @@
+module builtin
+
+fn print_libbacktrace(frames_to_skip int) {
+}

vlib/builtin/builtin_test.v

@@ -0,0 +1,14 @@
+fn test_g_main_argc() {
+	assert g_main_argc > 0
+}
+
+fn test_g_main_argv() {
+	assert g_main_argv != 0
+	mut first_arg := ''
+	$if windows {
+		first_arg = unsafe { string_from_wide(&&u16(g_main_argv)[0]) }
+	} $else {
+		first_arg = unsafe { cstring_to_vstring(&&char(g_main_argv)[0]) }
+	}
+	assert first_arg.contains('builtin_test')
+}

vlib/v/gen/c/cmain.v

@@ -72,6 +72,8 @@ fn (mut g Gen) gen_c_main_function_header() {
 	} else {
 		g.writeln('int main(int ___argc, char** ___argv){')
 	}
+	g.writeln('\tg_main_argc = ___argc;')
+	g.writeln('\tg_main_argv = ___argv;')
 }
 
 fn (mut g Gen) gen_c_main_header() {