fix some unchecked return value warnings

From: Stefan Bühler <stbuehler@web.de>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@3015 152afb58-edef-0310-8abb-c4023f1b3aa9

NEWS

@@ -10,6 +10,7 @@ NEWS
   * increase upload temporary chunk file size from 1MB to 16MB
   * fix undefined integer shift
   * rewrite network sendfile/mmap/writev/write backends
+  * fix some unchecked return value warnings
 
 - 1.4.36 - 2015-07-26
   * use keep-alive timeout while waiting for HTTP headers; use always the read timeout while waiting for the HTTP body

src/configfile.c

@@ -1045,7 +1045,7 @@ int config_parse_cmd(server *srv, config_t *context, const char *cmd) {
 
 	if (NULL == (oldpwd = getCWD())) {
 		log_error_write(srv, __FILE__, __LINE__, "s",
-				"cannot get cwd", strerror(errno));
+			"cannot get cwd", strerror(errno));
 		return -1;
 	}
 
@@ -1053,12 +1053,16 @@ int config_parse_cmd(server *srv, config_t *context, const char *cmd) {
 	out = buffer_init();
 
 	if (!buffer_string_is_empty(context->basedir)) {
-		chdir(context->basedir->ptr);
+		if (0 != chdir(context->basedir->ptr)) {
+			log_error_write(srv, __FILE__, __LINE__, "sbs",
+				"cannot change directory to", context->basedir, strerror(errno));
+			return -1;
+		}
 	}
 
 	if (0 != proc_open_buffer(cmd, NULL, out, NULL)) {
 		log_error_write(srv, __FILE__, __LINE__, "sbss",
-				"opening", source, "failed:", strerror(errno));
+			"opening", source, "failed:", strerror(errno));
 		ret = -1;
 	} else {
 		tokenizer_init(&t, source, CONST_BUF_LEN(out));
@@ -1067,7 +1071,11 @@ int config_parse_cmd(server *srv, config_t *context, const char *cmd) {
 
 	buffer_free(source);
 	buffer_free(out);
-	chdir(oldpwd);
+	if (0 != chdir(oldpwd)) {
+		log_error_write(srv, __FILE__, __LINE__, "sss",
+			"cannot change directory to", oldpwd, strerror(errno));
+		return -1;
+	}
 	free(oldpwd);
 	return ret;
 }

src/log.c

@@ -26,6 +26,36 @@
 # define O_LARGEFILE 0
 #endif
 
+/* retry write on EINTR or when not all data was written */
+ssize_t write_all(int fd, const void* buf, size_t count) {
+	ssize_t written = 0;
+
+	while (count > 0) {
+		ssize_t r = write(fd, buf, count);
+		if (r < 0) {
+			switch (errno) {
+			case EINTR:
+				/* try again */
+				break;
+			default:
+				/* fail - repeating probably won't help */
+				return -1;
+			}
+		} else if (0 == r) {
+			/* really shouldn't happen... */
+			errno = EIO;
+			return -1;
+		} else {
+			force_assert(r <= (ssize_t) count);
+			written += r;
+			buf = r + (char const*) buf;
+			count -= r;
+		}
+	}
+
+	return written;
+}
+
 /* Close fd and _try_ to get a /dev/null for it instead.
  * close() alone may trigger some bugs when a
  * process opens another file and gets fd = STDOUT_FILENO or STDERR_FILENO
@@ -361,7 +391,7 @@ static void log_write(server *srv, buffer *b) {
 	case ERRORLOG_FILE:
 	case ERRORLOG_FD:
 		buffer_append_string_len(b, CONST_STR_LEN("\n"));
-		write(srv->errorlog_fd, CONST_BUF_LEN(b));
+		write_all(srv->errorlog_fd, CONST_BUF_LEN(b));
 		break;
 	case ERRORLOG_SYSLOG:
 		syslog(LOG_ERR, "%s", b->ptr);

src/log.h

@@ -3,6 +3,8 @@
 
 #include "server.h"
 
+ssize_t write_all(int fd, const void* buf, size_t count);
+
 /* Close fd and _try_ to get a /dev/null for it instead.
  * Returns 0 on success and -1 on failure (fd gets closed in all cases)
  */

src/mod_accesslog.c

@@ -160,6 +160,13 @@ INIT_FUNC(mod_accesslog_init) {
 	return p;
 }
 
+static void accesslog_write_all(server *srv, const buffer *filename, int fd, const void* buf, size_t count) {
+	if (-1 == write_all(fd, buf, count)) {
+		log_error_write(srv, __FILE__, __LINE__, "sbs",
+			"writing access log entry failed:", filename, strerror(errno));
+	}
+}
+
 static void accesslog_append_escaped(buffer *dest, buffer *str) {
 	char *ptr, *start, *end;
 
@@ -418,7 +425,7 @@ FREE_FUNC(mod_accesslog_free) {
 
 			if (!buffer_string_is_empty(s->access_logbuffer)) {
 				if (s->log_access_fd != -1) {
-					write(s->log_access_fd, CONST_BUF_LEN(s->access_logbuffer));
+					accesslog_write_all(srv, s->access_logfile, s->log_access_fd, CONST_BUF_LEN(s->access_logbuffer));
 				}
 			}
 
@@ -593,7 +600,7 @@ SIGHUP_FUNC(log_access_cycle) {
 
 		if (!buffer_string_is_empty(s->access_logbuffer)) {
 			if (s->log_access_fd != -1) {
-				write(s->log_access_fd, CONST_BUF_LEN(s->access_logbuffer));
+				accesslog_write_all(srv, s->access_logfile, s->log_access_fd, CONST_BUF_LEN(s->access_logbuffer));
 			}
 
 			buffer_reset(s->access_logbuffer);
@@ -914,7 +921,7 @@ REQUESTDONE_FUNC(log_access_write) {
 			}
 #endif
 		} else if (p->conf.log_access_fd != -1) {
-			write(p->conf.log_access_fd, CONST_BUF_LEN(b));
+			accesslog_write_all(srv, p->conf.access_logfile, p->conf.log_access_fd, CONST_BUF_LEN(b));
 		}
 		buffer_reset(b);
 	}

src/server.c

@@ -366,7 +366,7 @@ static void show_version (void) {
 "Build-Date: " __DATE__ " " __TIME__ "\n";
 ;
 #undef TEXT_SSL
-	write(STDOUT_FILENO, b, strlen(b));
+	write_all(STDOUT_FILENO, b, strlen(b));
 }
 
 static void show_features (void) {
@@ -535,7 +535,7 @@ static void show_help (void) {
 ;
 #undef TEXT_SSL
 #undef TEXT_IPV6
-	write(STDOUT_FILENO, b, strlen(b));
+	write_all(STDOUT_FILENO, b, strlen(b));
 }
 
 int main (int argc, char **argv) {
@@ -1001,7 +1001,11 @@ int main (int argc, char **argv) {
 	if (pid_fd != -1) {
 		buffer_copy_int(srv->tmp_buf, getpid());
 		buffer_append_string_len(srv->tmp_buf, CONST_STR_LEN("\n"));
-		write(pid_fd, CONST_BUF_LEN(srv->tmp_buf));
+		if (-1 == write_all(pid_fd, CONST_BUF_LEN(srv->tmp_buf))) {
+			log_error_write(srv, __FILE__, __LINE__, "ss", "Couldn't write pid file:", strerror(errno));
+			close(pid_fd);
+			return -1;
+		}
 		close(pid_fd);
 		pid_fd = -1;
 	}