On 3/30/20 9:07 PM, Brice Goglin wrote:
When the program name is very long, qemu-user may truncate it in
/proc/self/stat. However the truncation must keep the ending ") "
to conform to the proc manpage which says:
(2) comm %s
The filename of the executable, in parentheses. This
is visible whether or not the executable is swapped
out.
To reproduce:
$ ln -s /bin/cat <filenamewithmorethan128chars>
$ qemu-x86_64 ./<filenamewithmorethan128chars> /proc/self/stat
Before the patch, you get:
1134631 (<filenametruncated>0 0 0 0 0 0 0 0 ...
After the patch:
1134631 (<filenametruncat>) 0 0 0 0 0 0 0 0 ...
This fixes an issue with hwloc failing to parse /proc/self/stat
when Ludovic Courtes was testing it in guix over qemu-aarch64.
Signed-off-by: Brice Goglin<brice.gog...@inria.fr>
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 5af55fca78..a1126dcf5b 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7305,7 +7305,10 @@ static int open_self_stat(void *cpu_env, int fd)
snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
} else if (i == 1) {
/* app name */
- snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
+ len = snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
+ if (len >= sizeof(buf))
+ /* bring back the ending ") " that was truncated */
+ strcpy(buf+sizeof(buf)-3, ") ");
Maybe we can avoid the sprintf() call:
-- >8 --
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7305,7 +7305,11 @@ static int open_self_stat(void *cpu_env, int fd)
snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
} else if (i == 1) {
/* app name */
- snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
+ char *ptr = buf;
+
+ *ptr++ = '(';
+ ptr = stpncpy(ptr, ts->bprm->argv[0], sizeof(buf) - 3);
+ strcpy(ptr, ") ");
} else if (i == 27) {
/* stack bottom */
val = start_stack;
---
} else if (i == 27) {
/* stack bottom */
val = start_stack;
