fdo-mirrors/mesa
1
0
Fork 0
mirror of https://gitlab.freedesktop.org/mesa/mesa.git synced 2026-05-05 07:28:11 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions 2

util/os_file: always use the 'grow' mechanism

Browse source 
Use fstat() only to pre-allocate a big enough buffer.

This fixes a race where if the file grows between fstat() and read()
we would be missing the end of the file, and if the file slims down
read() would just fail.

Fixes: 316964709e "util: add os_read_file() helper"
Reported-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
(cherry picked from commit 22c1657d05)
This commit is contained in:
Eric Engestrom 2019-05-01 11:44:16 +01:00 • committed by Juan A. Suarez Romero
parent 5fcfcdb162
commit 7fa89fd959
1 changed files with 20 additions and 42 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

62
src/util/os_file.c
View file

@ -38,11 +38,29 @@ readN(int fd, char *buf, size_t len)
return total ? total : err;
}
static char *
read_grow(int fd)
char *
os_read_file(const char *filename)
{
/* Note that this also serves as a slight margin to avoid a 2x grow when
* the file is just a few bytes larger when we read it than when we
* fstat'ed it.
* The string's NULL terminator is also included in here.
*/
size_t len = 64;
int fd = open(filename, O_RDONLY);
if (fd == -1) {
/* errno set by open() */
return NULL;
}
/* Pre-allocate a buffer at least the size of the file if we can read
* that information.
*/
struct stat stat;
if (fstat(fd, &stat) == 0)
len += stat.st_size;
char *buf = malloc(len);
if (!buf) {
close(fd);
@ -77,46 +95,6 @@ read_grow(int fd)
return buf;
}
char *
os_read_file(const char *filename)
{
size_t len = 0;
int fd = open(filename, O_RDONLY);
if (fd == -1) {
/* errno set by open() */
return NULL;
}
struct stat stat;
if (fstat(fd, &stat) == 0)
len = stat.st_size;
if (!len)
return read_grow(fd);
/* add NULL terminator */
len++;
char *buf = malloc(len);
if (!buf) {
close(fd);
errno = -ENOMEM;
return NULL;
}
ssize_t read = readN(fd, buf, len - 1);
close(fd);
if (read == -1)
return NULL;
buf[read] = '\0';
return buf;
}
#else
char *