[PATCH] Verbose git-daemon logging

This patch makes git-daemon --verbose log some useful things on stderr -
in particular connects, disconnects and upload requests, and in such a
way to be able to trace a particular session. Some more errors are now
also logged (even when --verbose is not passed). It is still not perfect
since messages produced by the non-daemon-specific code are obviously
not formatted properly.

[jc: With minor fix up in the log line truncation, and
 use of write(2) as suggested by Linus.]

Signed-off-by: Petr Baudis <pasky@suse.cz>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/daemon.c b/daemon.c
index 5100cf2..4e63bb8 100644 (file)
--- a/daemon.c
+++ b/daemon.c
@@ -6,13 +6,70 @@
 #include <sys/time.h>
 #include <netdb.h>
 #include <netinet/in.h>
+#include <arpa/inet.h>
+
+static int verbose;
+
+static const char daemon_usage[] = "git-daemon [--verbose] [--inetd | --port=n]";
+
+
+static void logreport(const char *err, va_list params)
+{
+       /* We should do a single write so that it is atomic and output
+        * of several processes do not get intermingled. */
+       char buf[1024];
+       int buflen;
+       int maxlen, msglen;
+
+       /* sizeof(buf) should be big enough for "[pid] \n" */
+       buflen = snprintf(buf, sizeof(buf), "[%d] ", getpid());
+
+       maxlen = sizeof(buf) - buflen - 1; /* -1 for our own LF */
+       msglen = vsnprintf(buf + buflen, maxlen, err, params);
+
+       /* maxlen counted our own LF but also counts space given to
+        * vsnprintf for the terminating NUL.  We want to make sure that
+        * we have space for our own LF and NUL after the "meat" of the
+        * message, so truncate it at maxlen - 1.
+        */
+       if (msglen > maxlen - 1)
+               msglen = maxlen - 1;
+       else if (msglen < 0)
+               msglen = 0; /* Protect against weird return values. */
+       buflen += msglen;
+
+       buf[buflen++] = '\n';
+       buf[buflen] = '\0';
+
+       write(2, buf, buflen);
+}
+
+void logerror(const char *err, ...)
+{
+       va_list params;
+       va_start(params, err);
+       logreport(err, params);
+       va_end(params);
+}
+
+void lognotice(const char *err, ...)
+{
+       va_list params;
+       if (!verbose)
+               return;
+       va_start(params, err);
+       logreport(err, params);
+       va_end(params);
+}
 
-static const char daemon_usage[] = "git-daemon [--inetd | --port=n]";
 
 static int upload(char *dir, int dirlen)
 {
-       if (chdir(dir) < 0)
+       lognotice("Request for '%s'", dir);
+       if (chdir(dir) < 0) {
+               logerror("Cannot chdir('%s'): %s", dir, strerror(errno));
                return -1;
+       }
        chdir(".git");
 
        /*
@@ -24,8 +81,10 @@ static int upload(char *dir, int dirlen)
         */
        if (access("git-daemon-export-ok", F_OK) ||
            access("objects/00", X_OK) ||
-           access("HEAD", R_OK))
+           access("HEAD", R_OK)) {
+               logerror("Not a valid gitd-enabled repository: '%s'", dir);
                return -1;
+       }
 
        /*
         * We'll ignore SIGTERM from now on, we have a
@@ -51,7 +110,7 @@ static int execute(void)
        if (!strncmp("git-upload-pack /", line, 17))
                return upload(line + 16, len - 16);
 
-       fprintf(stderr, "got bad connection '%s'\n", line);
+       logerror("Protocol error: '%s'", line);
        return -1;
 }
 
@@ -181,6 +240,8 @@ static void check_max_connections(void)
 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 {
        pid_t pid = fork();
+       char addrbuf[256] = "";
+       int port = -1;
 
        if (pid) {
                unsigned idx;
@@ -200,6 +261,24 @@ static void handle(int incoming, struct sockaddr *addr, int addrlen)
        dup2(incoming, 0);
        dup2(incoming, 1);
        close(incoming);
+
+       if (addr->sa_family == AF_INET) {
+               struct sockaddr_in *sin_addr = (void *) addr;
+               inet_ntop(AF_INET, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
+               port = sin_addr->sin_port;
+
+       } else if (addr->sa_family == AF_INET6) {
+               struct sockaddr_in6 *sin6_addr = (void *) addr;
+
+               char *buf = addrbuf;
+               *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
+               inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
+               strcat(buf, "]");
+
+               port = sin6_addr->sin6_port;
+       }
+       lognotice("Connection from %s:%d", addrbuf, port);
+
        exit(execute());
 }
 
@@ -212,6 +291,9 @@ static void child_handler(int signo)
                        unsigned reaped = children_reaped;
                        dead_child[reaped % MAX_CHILDREN] = pid;
                        children_reaped = reaped + 1;
+                       /* XXX: Custom logging, since we don't wanna getpid() */
+                       if (verbose)
+                               fprintf(stderr, "[%d] Disconnected\n", pid);
                        continue;
                }
                break;
@@ -349,6 +431,10 @@ int main(int argc, char **argv)
                        inetd_mode = 1;
                        continue;
                }
+               if (!strcmp(arg, "--verbose")) {
+                       verbose = 1;
+                       continue;
+               }
 
                usage(daemon_usage);
        }