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

[Vladimir Nikulichev]

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 null 
characters
Saved corefile core.18706

There's nothing wrong, null characters separate command line arguments 
from
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 (struct 
elf_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 (struct 
elf_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 (struct 
elf_internal_linux_prpsinfo *p)
    /* Finally, obtaining the UID and GID.  For that, we read and 
parse 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 (const 
char *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.  */