[Mesa-dev] [PATCH 24/24] gallium/aux/os: Fix warning/handle failure to read from /proc/self/cmdline

[Gert Wollny]

Handle the failure to read from /proc/self/cmdline by printing an error
message and fix the -Wsign-compare warning:

In file included from ./util/u_memory.h:39:0,
                 from os/os_process.c:31:
os/os_process.c: In function 'os_get_command_line':
os/os_process.c:140:16: warning: comparison between signed and unsigned
integer expressions [-Wsign-compare]
       assert(n < size);
                ^
./util/u_debug.h:189:30: note: in definition of macro 'debug_assert'
 #define debug_assert(expr) ((expr) ? (void)0 :
_debug_assert_fail(#expr,
__FILE__, __LINE__, __FUNCTION__))
                              ^~~~
os/os_process.c:140:7: note: in expansion of macro 'assert'
       assert(n < size);
       ^~~~~~

gallium/aux/os/ squash

v2: - simplify patch (Emil Velikov)
    - print error message only when compiled in debug mode

Signed-off-by: Gert Wollny <gert.wollny at collabora.com>
---
 src/gallium/auxiliary/os/os_process.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/gallium/auxiliary/os/os_process.c b/src/gallium/auxiliary/os/os_process.c
index 035bd228e7..ed03b81f85 100644
--- a/src/gallium/auxiliary/os/os_process.c
+++ b/src/gallium/auxiliary/os/os_process.c
@@ -29,6 +29,7 @@
 #include "pipe/p_config.h"
 #include "os/os_process.h"
 #include "util/u_memory.h"
+#include <strings.h>
 
 #if defined(PIPE_SUBSYSTEM_WINDOWS_USER)
 #  include <windows.h>
@@ -135,9 +136,18 @@ os_get_command_line(char *cmdline, size_t size)
 #elif defined(PIPE_OS_LINUX)
    int f = open("/proc/self/cmdline", O_RDONLY);
    if (f) {
-      const int n = read(f, cmdline, size - 1);
+      const ssize_t n = read(f, cmdline, size - 1);
       int i;
-      assert(n < size);
+
+      if (n == -1) {
+         debug_printf("Error reading from /proc/self/cmdline: %s",
+                      strerror(errno));
+         close(f);
+         cmdline[0] = 0;
+         return FALSE;
+      }
+
+      assert((size_t)n < size);
       // The arguments are separated by '\0' chars.  Convert them to spaces.
       for (i = 0; i < n; i++) {
          if (cmdline[i] == 0) {
-- 
2.17.1