Obtain absoute path of configuration file, expose it in INFO.

src/redis.c

@@ -1163,6 +1163,7 @@ void createSharedObjects(void) {
 
 void initServerConfig() {
     getRandomHexChars(server.runid,REDIS_RUN_ID_SIZE);
+    server.configfile = NULL;
     server.hz = REDIS_DEFAULT_HZ;
     server.runid[REDIS_RUN_ID_SIZE] = '\0';
     server.arch_bits = (sizeof(long) == 8) ? 64 : 32;
@@ -2006,7 +2007,8 @@ sds genRedisInfoString(char *section) {
             "uptime_in_seconds:%ld\r\n"
             "uptime_in_days:%ld\r\n"
             "hz:%d\r\n"
-            "lru_clock:%ld\r\n",
+            "lru_clock:%ld\r\n"
+            "config_file:%s\r\n",
             REDIS_VERSION,
             redisGitSHA1(),
             strtol(redisGitDirty(),NULL,10) > 0,
@@ -2026,7 +2028,8 @@ sds genRedisInfoString(char *section) {
             uptime,
             uptime/(3600*24),
             server.hz,
-            (unsigned long) server.lruclock);
+            (unsigned long) server.lruclock,
+            server.configfile ? server.configfile : "");
     }
 
     /* Clients */
@@ -2689,6 +2692,58 @@ void redisSetProcTitle(char *title) {
 #endif
 }
 
+/* Given the filename, return the absolute path as an SDS string, or NULL
+ * if it fails for some reason. Note that "filename" may be an absolute path
+ * already, this will be detected and handled correctly.
+ *
+ * The function does not try to normalize everything, but only the obvious
+ * case of one or more "../" appearning at the start of "filename"
+ * relative path. */
+sds getAbsolutePath(char *filename) {
+    char cwd[1024];
+    sds abspath;
+    sds relpath = sdsnew(filename);
+
+    relpath = sdstrim(relpath," \r\n\t");
+    if (relpath[0] == '/') return relpath; /* Path is already absolute. */
+
+    /* If path is relative, join cwd and relative path. */
+    if (getcwd(cwd,sizeof(cwd)) == NULL) {
+        sdsfree(relpath);
+        return NULL;
+    }
+    abspath = sdsnew(cwd);
+    if (sdslen(abspath) && abspath[sdslen(abspath)-1] != '/')
+        abspath = sdscat(abspath,"/");
+
+    /* At this point we have the current path always ending with "/", and
+     * the trimmed relative path. Try to normalize the obvious case of
+     * trailing ../ elements at the start of the path.
+     *
+     * For every "../" we find in the filename, we remove it and also remove
+     * the last element of the cwd, unless the current cwd is "/". */
+    while (sdslen(relpath) >= 3 &&
+           relpath[0] == '.' && relpath[1] == '.' && relpath[2] == '/')
+    {
+        relpath = sdsrange(relpath,3,-1);
+        if (sdslen(abspath) > 1) {
+            char *p = abspath + sdslen(abspath)-2;
+            int trimlen = 1;
+
+            while(*p != '/') {
+                p--;
+                trimlen++;
+            }
+            abspath = sdsrange(abspath,0,-(trimlen+1));
+        }
+    }
+
+    /* Finally glue the two parts together. */
+    abspath = sdscatsds(abspath,relpath);
+    sdsfree(relpath);
+    return abspath;
+}
+
 int main(int argc, char **argv) {
     struct timeval tv;
 
@@ -2756,6 +2811,7 @@ int main(int argc, char **argv) {
         resetServerSaveParams();
         loadServerConfig(configfile,options);
         sdsfree(options);
+        if (configfile) server.configfile = getAbsolutePath(configfile);
     } else {
         redisLog(REDIS_WARNING, "Warning: no config file specified, using the default config. In order to specify a config file use %s /path/to/%s.conf", argv[0], server.sentinel_mode ? "sentinel" : "redis");
     }

src/redis.h

@@ -519,6 +519,7 @@ typedef struct redisOpArray {
 
 struct redisServer {
     /* General */
+    char *configfile;           /* Absolute config file path, or NULL */
     int hz;                     /* serverCron() calls frequency in hertz */
     redisDb *db;
     dict *commands;             /* Command table */