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os: handle fread errors (#9687)

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Henrixounez 2021-04-12 09:26:08 +02:00 committed by GitHub
parent 6d2d956c80
commit 7ba13a415a
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@ -21,6 +21,10 @@ fn C.open(&char, int, ...int) int
fn C.fdopen(fd int, mode &char) &C.FILE
fn C.ferror(stream &C.FILE) int
fn C.feof(stream &C.FILE) int
fn C.CopyFile(&u16, &u16, bool) int
// fn C.lstat(charptr, voidptr) u64
@ -101,11 +105,24 @@ pub fn read_file(path string) ?string {
unsafe {
mut str := malloc(fsize + 1)
nelements := int(C.fread(str, fsize, 1, fp))
if nelements == 0 && fsize > 0 {
is_eof := int(C.feof(fp))
is_error := int(C.ferror(fp))
if is_eof == 0 && is_error != 0 {
free(str)
return error('fread failed')
}
str[fsize] = 0
if nelements == 0 {
// It is highly likely that the file was a virtual file from
// /sys or /proc, with information generated on the fly, so
// fsize was not reliably reported. Using vstring() here is
// slower (it calls strlen internally), but will return more
// consistent results.
// For example reading from /sys/class/sound/card0/id produces
// a `PCH\n` string, but fsize is 4096, and otherwise you would
// get a V string with .len = 4096 and .str = "PCH\n\\000".
return str.vstring()
}
return str.vstring_with_len(fsize)
}
}