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fileio: read_virtual_file(): on last attempt ignore file size

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Apparently the reported file size was misleading on this file, hence
ignore it on our last loop attempt and just pretend it wasn't reported
at all.
This commit is contained in:
Lennart Poettering 2021-05-21 17:40:19 +02:00
parent eff722c693
commit b2d0b90f54
1 changed files with 11 additions and 14 deletions
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25
src/basic/fileio.c
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@ -404,7 +404,10 @@ int read_virtual_file(const char *filename, size_t max_size, char **ret_contents
/* Be prepared for files from /proc which generally report a file size of 0. */
assert_cc(READ_FULL_BYTES_MAX < SSIZE_MAX);
if (st.st_size > 0) {
if (st.st_size > 0 && n_retries > 1) {
/* Let's use the file size if we have more than 1 attempt left. On the last attempt
* we'll ignore the file size */
if (st.st_size > SSIZE_MAX) { /* Avoid overflow with 32-bit size_t and 64-bit off_t. */
if (max_size == SIZE_MAX)
@ -427,6 +430,7 @@ int read_virtual_file(const char *filename, size_t max_size, char **ret_contents
buf = malloc(size + 1);
if (!buf)
return -ENOMEM;
/* Use a bigger allocation if we got it anyway, but not more than the limit. */
size = MIN3(MALLOC_SIZEOF_SAFE(buf) - 1, max_size, READ_FULL_BYTES_MAX);
@ -457,20 +461,13 @@ int read_virtual_file(const char *filename, size_t max_size, char **ret_contents
break;
}
/* Hmm... either we read too few bytes from /proc or less likely the content
* of the file might have been changed (and is now bigger) while we were
* processing, let's try again either with a bigger guessed size or the new
* file size. */
/* We have no further attempts left? Then the file is apparently larger than our limits. Give up. */
if (n_retries <= 0)
return -EFBIG;
if (n_retries <= 0) {
if (max_size == SIZE_MAX)
return st.st_size > 0 ? -EIO : -EFBIG;
/* Accept a short read, but truncate it appropropriately. */
n = MIN(n, max_size);
truncated = true;
break;
}
/* Hmm... either we read too few bytes from /proc or less likely the content of the file
* might have been changed (and is now bigger) while we were processing, let's try again
* either with the new file size. */
if (lseek(fd, 0, SEEK_SET) < 0)
return -errno;