daemon: collect list of called external commands

guestfsd calls many different tools. Keeping track of all of them is
error prone. This patch introduces a new helper macro to put the command
string into its own ELF section:

GUESTFSD_EXT_CMD(C_variable, command_name);

This syntax makes it still possible to grep for used command names.

The actual usage of the collected list could be like this:

  objcopy -j .guestfsd_ext_cmds -O binary daemon/guestfsd /dev/stdout |
  tr '\0' '\n' | sort -u

The resulting output will be used to tell mkinitrd which programs to
copy into the initrd.

Signed-off-by: Olaf Hering <olaf@aepfle.de>

RWMJ:
 - Move str_vgchange at request of author.
 - Fix snprintf call in daemon/debug.c

1 files changed, 20 insertions, 9 deletions

diff --git a/daemon/debug.c b/daemon/debug.c
index 97d21f03..41bae38b 100644
--- a/daemon/debug.c
+++ b/daemon/debug.c
@@ -32,6 +32,15 @@
 #include "daemon.h"
 #include "actions.h"
 
+GUESTFSD_EXT_CMD(str_printenv, printenv);
+GUESTFSD_EXT_CMD(str_ldd, ldd);
+GUESTFSD_EXT_CMD(str_ls, ls);
+GUESTFSD_EXT_CMD(str_find, find);
+GUESTFSD_EXT_CMD(str_xargs, xargs);
+GUESTFSD_EXT_CMD(str_file, file);
+GUESTFSD_EXT_CMD(str_grep, grep);
+GUESTFSD_EXT_CMD(str_gawk, gawk);
+
 /* This command exposes debugging information, internals and
  * status.  There is no comprehensive documentation for this
  * command.  You have to look at the source code in this file
@@ -275,7 +284,7 @@ debug_env (const char *subcmd, size_t argc, char *const *const argv)
   int r;
   char *out, *err;
 
-  r = command (&out, &err, "printenv", NULL);
+  r = command (&out, &err, str_printenv, NULL);
   if (r == -1) {
     reply_with_error ("printenv: %s", err);
     free (out);
@@ -318,12 +327,14 @@ debug_binaries (const char *subcmd, size_t argc, char *const *const argv)
 {
   int r;
   char *out, *err;
+  char cmd[256];
 
-  const char cmd[] =
-    "find / -xdev -type f -executable "
-    "| xargs file -i "
-    "| grep application/x-executable "
-    "| gawk -F: '{print $1}'";
+  snprintf (cmd, sizeof (cmd),
+            "%s / -xdev -type f -executable "
+            "| %s %s -i "
+            "| %s application/x-executable "
+            "| %s -F: '{print $1}'",
+            str_find, str_xargs, str_file, str_grep, str_gawk);
 
   r = command (&out, &err, "sh", "-c", cmd, NULL);
   if (r == -1) {
@@ -358,7 +369,7 @@ debug_ldd (const char *subcmd, size_t argc, char *const *const argv)
    * Also 'ldd' randomly sends messages to stderr and errors to stdout
    * depending on the phase of the moon.
    */
-  r = command (&out, &err, "ldd", "-r", argv[0], NULL);
+  r = command (&out, &err, str_ldd, "-r", argv[0], NULL);
   if (r == -1) {
     reply_with_error ("ldd: %s: %s", argv[0], err);
     free (out);
@@ -389,7 +400,7 @@ debug_ls (const char *subcmd, size_t argc, char *const *const argv)
   const char *cargv[len+3];
   size_t i;
 
-  cargv[0] = "ls";
+  cargv[0] = str_ls;
   cargv[1] = "-a";
   for (i = 0; i < len; ++i)
     cargv[2+i] = argv[i];
@@ -419,7 +430,7 @@ debug_ll (const char *subcmd, size_t argc, char *const *const argv)
   const char *cargv[len+3];
   size_t i;
 
-  cargv[0] = "ls";
+  cargv[0] = str_ls;
   cargv[1] = "-la";
   for (i = 0; i < len; ++i)
     cargv[2+i] = argv[i];