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gamemode: Add a tiny buffered snprintf helper

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Be careful using this as it may introduce some non-obvious pitfalls.
This saves us from a heap allocation in some code locations.

Signed-off-by: Kai Krakow <kai@kaishome.de>
This commit is contained in:
Kai Krakow 2018-10-03 15:21:33 +02:00
parent 4fd93ee30a
commit d023495a5d
1 changed files with 12 additions and 4 deletions
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16
daemon/gamemode.c
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@ -70,6 +70,11 @@ POSSIBILITY OF SUCH DAMAGE.
*/
#define CLAMP(lbound, ubound, value) MIN(MIN(lbound, ubound), MAX(MAX(lbound, ubound), value))
/* Little helper to safely print into a buffer, returns a pointer into the buffer
*/
#define buffered_snprintf(b, s, ...) \
(snprintf(b, sizeof(b), s, __VA_ARGS__) < (ssize_t)sizeof(b) ? b : NULL)
/* Little helper to safely print into a buffer, returns a newly allocated string
*/
#define safe_snprintf(b, s, ...) \
@ -753,6 +758,11 @@ static char *game_mode_resolve_wine_preloader(pid_t pid)
char *proc_path = NULL, *wine_exe = NULL, *wineprefix = NULL;
int proc_fd = -1;
/* We could use the buffered_snprintf() helper here but it may potentially
* overwrite proc_path when the buffer is re-used later and usage of
* proc_path has not been discarded yet (i.e., it's used in the fail path).
* Let's not introduce this non-obvious pitfall.
*/
if (!(proc_path = safe_snprintf(buffer, "/proc/%d", pid)))
goto fail;
@ -818,10 +828,9 @@ static char *game_mode_resolve_wine_preloader(pid_t pid)
wine_exe[0] = (char)tolower(wine_exe[0]);
/* Convert relative wine exe path to full unix path */
char *wine_path = safe_snprintf(buffer, "%s/dosdevices/%s", wineprefix, wine_exe);
char *wine_path = buffered_snprintf(buffer, "%s/dosdevices/%s", wineprefix, wine_exe);
free(wine_exe);
wine_exe = wine_path ? realpath(wine_path, NULL) : NULL;
free(wine_path);
/* Fine? Successo? Fortuna! */
if (wine_exe)
@ -861,12 +870,11 @@ static char *game_mode_context_find_exe(pid_t pid)
char buffer[PATH_MAX];
char *proc_path = NULL, *wine_exe = NULL;
if (!(proc_path = safe_snprintf(buffer, "/proc/%d/exe", pid)))
if (!(proc_path = buffered_snprintf(buffer, "/proc/%d/exe", pid)))
goto fail;
/* Allocate the realpath if possible */
char *exe = realpath(proc_path, NULL);
free(proc_path);
if (!exe)
goto fail;