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[PATCH] Disable check for NUL bytes in /proc/pid/cmdline

From: "Vladimir Nikulichev" <nvs at tbricks dot com>
To: gdb-patches at sourceware dot org
Date: Fri, 11 Apr 2014 18:28:55 +0400
Subject: [PATCH] Disable check for NUL bytes in /proc/pid/cmdline
Authentication-results: sourceware.org; auth=none

When I execute gcore on a process, it prints warning that/proc/pid/cmdline

contains null characters:

$ gcore 18706
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
0x00007fa23be3c5c3 in __select_nocancel () from /lib64/libc.so.6

warning: target file /proc/18706/cmdline contained unexpected nullcharacters

Saved corefile core.18706

There's nothing wrong, null characters separate command line argumentsfrom

each other. This fix disables the check when reading cmdline.

gdb:

2014-04-10  Vladimir Nikulichev  <nvs@tbricks.com>

	* target.h (target_fileio_read_stralloc): Add
	'check_null' argument.
	* target.c (target_fileio_read_stralloc): Make
	check for NULs optional.
	* linux-tdep.c (linux_info_proc, linux_fill_prpsinfo):
	Disable check for NULs in /proc/pid/cmdline.

---

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 45a94a8..8da7244 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,12 @@
+2014-04-10  Vladimir Nikulichev  <nvs@tbricks.com>
+
+	* target.h (target_fileio_read_stralloc): Add
+	'check_null' argument.
+	* target.c (target_fileio_read_stralloc): Make
+	check for NULs optional.
+	* linux-tdep.c (linux_info_proc, linux_fill_prpsinfo):
+	Disable check for NULs in /proc/pid/cmdline.
+
 2014-04-10  Pedro Alves  <palves@redhat.com>

 	* breakpoint.c (single_step_breakpoints)
diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index c10b8ee..4391e1a 100644
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c

@@ -351,7 +351,7 @@ linux_info_proc (struct gdbarch *gdbarch, char*args,

   if (cmdline_f)
     {

xsnprintf (filename, sizeof filename, "/proc/%ld/cmdline",pid);

-      data = target_fileio_read_stralloc (filename);
+      data = target_fileio_read_stralloc (filename, 0);
       if (data)
 	{
 	  struct cleanup *cleanup = make_cleanup (xfree, data);

@@ -390,7 +390,7 @@ linux_info_proc (struct gdbarch *gdbarch, char*args,

   if (mappings_f)
     {
       xsnprintf (filename, sizeof filename, "/proc/%ld/maps", pid);
-      data = target_fileio_read_stralloc (filename);
+      data = target_fileio_read_stralloc (filename, 1);
       if (data)
 	{
 	  struct cleanup *cleanup = make_cleanup (xfree, data);

@@ -451,7 +451,7 @@ linux_info_proc (struct gdbarch *gdbarch, char*args,

   if (status_f)
     {

xsnprintf (filename, sizeof filename, "/proc/%ld/status",pid);

-      data = target_fileio_read_stralloc (filename);
+      data = target_fileio_read_stralloc (filename, 1);
       if (data)
 	{
 	  struct cleanup *cleanup = make_cleanup (xfree, data);

@@ -464,7 +464,7 @@ linux_info_proc (struct gdbarch *gdbarch, char*args,

   if (stat_f)
     {
       xsnprintf (filename, sizeof filename, "/proc/%ld/stat", pid);
-      data = target_fileio_read_stralloc (filename);
+      data = target_fileio_read_stralloc (filename, 1);
       if (data)
 	{
 	  struct cleanup *cleanup = make_cleanup (xfree, data);

@@ -753,13 +753,13 @@ linux_find_memory_regions_full (struct gdbarch*gdbarch,


   xsnprintf (mapsfilename, sizeof mapsfilename,
 	     "/proc/%d/smaps", current_inferior ()->pid);
-  data = target_fileio_read_stralloc (mapsfilename);
+  data = target_fileio_read_stralloc (mapsfilename, 1);
   if (data == NULL)
     {
       /* Older Linux kernels did not support /proc/PID/smaps.  */
       xsnprintf (mapsfilename, sizeof mapsfilename,
 		 "/proc/%d/maps", current_inferior ()->pid);
-      data = target_fileio_read_stralloc (mapsfilename);
+      data = target_fileio_read_stralloc (mapsfilename, 1);
     }
   if (data)
     {

@@ -1273,7 +1273,7 @@ linux_fill_prpsinfo (structelf_internal_linux_prpsinfo *p)

   /* Obtaining PID and filename.  */
   pid = ptid_get_pid (inferior_ptid);

xsnprintf (filename, sizeof (filename), "/proc/%d/cmdline", (int)pid);

-  fname = target_fileio_read_stralloc (filename);
+  fname = target_fileio_read_stralloc (filename, 0);

   if (fname == NULL || *fname == '\0')
     {

@@ -1306,7 +1306,7 @@ linux_fill_prpsinfo (structelf_internal_linux_prpsinfo *p)

   p->pr_psargs[sizeof (p->pr_psargs) - 1] = '\0';

xsnprintf (filename, sizeof (filename), "/proc/%d/stat", (int)pid);

-  proc_stat = target_fileio_read_stralloc (filename);
+  proc_stat = target_fileio_read_stralloc (filename, 1);
   make_cleanup (xfree, proc_stat);

   if (proc_stat == NULL || *proc_stat == '\0')

@@ -1387,7 +1387,7 @@ linux_fill_prpsinfo (structelf_internal_linux_prpsinfo *p)/* Finally, obtaining the UID and GID. For that, we read andparse the

      contents of the `/proc/PID/status' file.  */

xsnprintf (filename, sizeof (filename), "/proc/%d/status", (int)pid);

-  proc_status = target_fileio_read_stralloc (filename);
+  proc_status = target_fileio_read_stralloc (filename, 1);
   make_cleanup (xfree, proc_status);

   if (proc_status == NULL || *proc_status == '\0')
diff --git a/gdb/target.c b/gdb/target.c
index 1b48f79..e6f9c3c 100644
--- a/gdb/target.c
+++ b/gdb/target.c

@@ -2895,7 +2895,7 @@ target_fileio_read_alloc (const char *filename,gdb_byte **buf_p)

    if the result contains any embedded NUL bytes.  */

 char *
-target_fileio_read_stralloc (const char *filename)
+target_fileio_read_stralloc (const char *filename, int check_null)
 {
   gdb_byte *buffer;
   char *bufstr;

@@ -2912,6 +2912,9 @@ target_fileio_read_stralloc (const char*filename)


   bufstr[transferred] = 0;

+  if (!check_null)
+    return bufstr;
+
   /* Check for embedded NUL bytes; but allow trailing NULs.  */
   for (i = strlen (bufstr); i < transferred; i++)
     if (bufstr[i] != 0)
diff --git a/gdb/target.h b/gdb/target.h
index d7c6c3d..2d11a99 100644
--- a/gdb/target.h
+++ b/gdb/target.h

@@ -1890,7 +1890,8 @@ extern LONGEST target_fileio_read_alloc (constchar *filename,

    or the transfer is unsupported, NULL is returned.  Empty objects
    are returned as allocated but empty strings.  A warning is issued
    if the result contains any embedded NUL bytes.  */
-extern char *target_fileio_read_stralloc (const char *filename);
+extern char *target_fileio_read_stralloc (const char *filename,
+					  int check_null);


 /* Tracepoint-related operations.  */

Follow-Ups:
- Re: [PATCH] Disable check for NUL bytes in /proc/pid/cmdline
  - From: Sergio Durigan Junior
- Re: [PATCH] Disable check for NUL bytes in /proc/pid/cmdline
  - From: Pedro Alves

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