make find_pid_by_name look at /proc/PID/exe too

function                                             old     new   delta
procps_scan                                         1642    1709     +67
find_pid_by_name                                     193     223     +30
free_procps_scan                                      29      37      +8

Signed-off-by: Alexander Shishkin <virtuoso@slind.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 27 insertions, 16 deletions

diff --git a/include/libbb.h b/include/libbb.h
index c7b4de13c..51ac69ed5 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1280,6 +1280,7 @@ typedef struct procps_status_t {
 /* Fields are set to 0/NULL if failed to determine (or not requested) */
         uint16_t argv_len;
         char *argv0;
+        char *exe;
         IF_SELINUX(char *context;)
         /* Everything below must contain no ptrs to malloc'ed data:
          * it is memset(0) for each process in procps_scan() */
@@ -1327,7 +1328,7 @@ enum {
         PSSCAN_COMM     = 1 << 5,
         /* PSSCAN_CMD      = 1 << 6, - use read_cmdline instead */
         PSSCAN_ARGV0    = 1 << 7,
-        /* PSSCAN_EXE      = 1 << 8, - not implemented */
+        PSSCAN_EXE      = 1 << 8,
         PSSCAN_STATE    = 1 << 9,
         PSSCAN_VSZ      = 1 << 10,
         PSSCAN_RSS      = 1 << 11,
diff --git a/libbb/find_pid_by_name.c b/libbb/find_pid_by_name.c
index 600d4e1a8..52a0c6dab 100644
--- a/libbb/find_pid_by_name.c
+++ b/libbb/find_pid_by_name.c
@@ -41,18 +41,20 @@ and therefore comm field contains "exe".
 static int comm_match(procps_status_t *p, const char *procName)
 {
         int argv1idx;
+        const char *argv1;
 
-        /* comm does not match */
         if (strncmp(p->comm, procName, 15) != 0)
-                return 0;
+                return 0; /* comm does not match */
 
-        /* in Linux, if comm is 15 chars, it may be a truncated */
-        if (p->comm[14] == '\0') /* comm is not truncated - match */
-                return 1;
+        /* In Linux, if comm is 15 chars, it is truncated.
+         * (or maybe the name was exactly 15 chars, but there is
+         * no way to know that) */
+        if (p->comm[14] == '\0')
+                return 1; /* comm is not truncated - matches */
 
         /* comm is truncated, but first 15 chars match.
          * This can be crazily_long_script_name.sh!
-         * The telltale sign is basename(argv[1]) == procName. */
+         * The telltale sign is basename(argv[1]) == procName */
 
         if (!p->argv0)
                 return 0;
@@ -60,8 +62,9 @@ static int comm_match(procps_status_t *p, const char *procName)
         argv1idx = strlen(p->argv0) + 1;
         if (argv1idx >= p->argv_len)
                 return 0;
+        argv1 = p->argv0 + argv1idx;
 
-        if (strcmp(bb_basename(p->argv0 + argv1idx), procName) != 0)
+        if (strcmp(bb_basename(argv1), procName) != 0)
                 return 0;
 
         return 1;
@@ -83,11 +86,12 @@ pid_t* FAST_FUNC find_pid_by_name(const char *procName)
         procps_status_t* p = NULL;
 
         pidList = xzalloc(sizeof(*pidList));
-        while ((p = procps_scan(p, PSSCAN_PID|PSSCAN_COMM|PSSCAN_ARGVN))) {
+        while ((p = procps_scan(p, PSSCAN_PID|PSSCAN_COMM|PSSCAN_ARGVN|PSSCAN_EXE))) {
                 if (comm_match(p, procName)
                 /* or we require argv0 to match (essential for matching reexeced /proc/self/exe)*/
                  || (p->argv0 && strcmp(bb_basename(p->argv0), procName) == 0)
-                /* TODO: we can also try /proc/NUM/exe link, do we want that? */
+                /* or we require /proc/PID/exe link to match */
+                 || (p->exe && strcmp(bb_basename(p->exe), procName) == 0)
                 ) {
                         pidList = xrealloc_vector(pidList, 2, i);
                         pidList[i++] = p->pid;
diff --git a/libbb/procps.c b/libbb/procps.c
index 6e122c4d5..307d8d622 100644
--- a/libbb/procps.c
+++ b/libbb/procps.c
@@ -111,6 +111,7 @@ void FAST_FUNC free_procps_scan(procps_status_t* sp)
 {
         closedir(sp->dir);
         free(sp->argv0);
+        free(sp->exe);
         IF_SELINUX(free(sp->context);)
         free(sp);
 }
@@ -213,7 +214,7 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
                 }
 #endif
 
-                filename_tail = filename + sprintf(filename, "/proc/%d", pid);
+                filename_tail = filename + sprintf(filename, "/proc/%u/", pid);
 
                 if (flags & PSSCAN_UIDGID) {
                         if (stat(filename, &sb))
@@ -230,7 +231,7 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
                         unsigned long vsz, rss;
 #endif
                         /* see proc(5) for some details on this */
-                        strcpy(filename_tail, "/stat");
+                        strcpy(filename_tail, "stat");
                         n = read_to_buf(filename, buf);
                         if (n < 0)
                                 break;
@@ -340,7 +341,7 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
                 if (flags & (PSSCAN_SMAPS)) {
                         FILE *file;
 
-                        strcpy(filename_tail, "/smaps");
+                        strcpy(filename_tail, "smaps");
                         file = fopen_for_read(filename);
                         if (!file)
                                 break;
@@ -390,7 +391,7 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
                 if (flags & PSSCAN_RUIDGID) {
                         FILE *file;
 
-                        strcpy(filename_tail, "/status");
+                        strcpy(filename_tail, "status");
                         file = fopen_for_read(filename);
                         if (!file)
                                 break;
@@ -415,7 +416,7 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
                         sp->argv0 = NULL;
                         free(sp->cmd);
                         sp->cmd = NULL;
-                        strcpy(filename_tail, "/cmdline");
+                        strcpy(filename_tail, "cmdline");
                         /* TODO: to get rid of size limits, read into malloc buf,
                          * then realloc it down to real size. */
                         n = read_to_buf(filename, buf);
@@ -436,7 +437,7 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
                 if (flags & (PSSCAN_ARGV0|PSSCAN_ARGVN)) {
                         free(sp->argv0);
                         sp->argv0 = NULL;
-                        strcpy(filename_tail, "/cmdline");
+                        strcpy(filename_tail, "cmdline");
                         n = read_to_buf(filename, buf);
                         if (n <= 0)
                                 break;
@@ -451,6 +452,11 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
                         }
                 }
 #endif
+                if (flags & PSSCAN_EXE) {
+                        strcpy(filename_tail, "exe");
+                        free(sp->exe);
+                        sp->exe = xmalloc_readlink(filename);
+                }
                 break;
         }
         return sp;