add util.c

Signed-off-by: Mattias Andrée <maandree@operamail.com>

5 files changed, 131 insertions, 51 deletions

diff --git a/Makefile b/Makefile
index fb7733f..4bcc9ea 100644
--- a/Makefile
+++ b/Makefile
@@ -60,7 +60,7 @@ C_FLAGS = $(OPTIMISE) $(WARN) -std=$(STD) $(CPPFLAGS) $(CFLAGS) $(LDFLAGS)  \
 
 
 # Object files for the libary
-LIBOBJ = linked-list hash-table fd-table mds-message
+LIBOBJ = linked-list hash-table fd-table mds-message util
 
 
 # Build rules.
diff --git a/src/libmdsserver/util.c b/src/libmdsserver/util.c
new file mode 100644
index 0000000..c4606e8
--- /dev/null
+++ b/src/libmdsserver/util.c
@@ -0,0 +1,82 @@
+/**
+ * mds — A micro-display server
+ * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "util.h"
+#include "config.h"
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <limits.h>
+#include <string.h>
+
+
+/**
+ * Read an environment variable, but handle it as undefined if empty
+ * 
+ * @param   var  The environment variable's name
+ * @return       The environment variable's value, `NULL` if empty or not defined
+ */
+char* getenv_nonempty(const char* var)
+{
+  char* rc = getenv(var);
+  if ((rc == NULL) || (*rc == '\0'))
+    return NULL;
+  return rc;
+}
+
+
+/**
+ * Re-exec the server.
+ * This function only returns on failure.
+ * 
+ * @param  argc      The number of elements in `argv`
+ * @param  argv      The command line arguments
+ * @param  reexeced  Whether the server has previously been re-exec:ed
+ */
+void reexec_server(int argc, char** argv, int reexeced)
+{
+  char readlink_buf[PATH_MAX];
+  ssize_t readlink_ptr;
+  char** reexec_args;
+  char** reexec_args_;
+  int i;
+  
+  /* Re-exec the server. */
+  readlink_ptr = readlink(SELF_EXE, readlink_buf, (sizeof(readlink_buf) / sizeof(char)) - 1);
+  if (readlink_ptr < 0)
+    return;
+  /* ‘readlink() does not append a null byte to buf.’ */
+  readlink_buf[readlink_ptr] = '\0';
+  reexec_args = alloca(((size_t)argc + 2) * sizeof(char*));
+  reexec_args_ = reexec_args;
+  if (reexeced == 0)
+    {
+      *reexec_args_++ = *argv;
+      *reexec_args_ = strdup("--re-exec");
+      if (*reexec_args_)
+	return;
+      for (i = 1; i < argc; i++)
+	reexec_args_[i] = argv[i];
+    }
+  else /* Don't let the --re-exec:s accumulate. */
+    *reexec_args_ = *argv;
+  for (i = 1; i < argc; i++)
+    reexec_args_[i] = argv[i];
+  reexec_args_[argc] = NULL;
+  execv(readlink_buf, reexec_args);
+}
+
diff --git a/src/libmdsserver/util.h b/src/libmdsserver/util.h
new file mode 100644
index 0000000..f1276f7
--- /dev/null
+++ b/src/libmdsserver/util.h
@@ -0,0 +1,43 @@
+/**
+ * mds — A micro-display server
+ * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef MDS_LIBMDSSERVER_UTIL_H
+#define MDS_LIBMDSSERVER_UTIL_H
+
+
+/**
+ * Read an environment variable, but handle it as undefined if empty
+ * 
+ * @param   var  The environment variable's name
+ * @return       The environment variable's value, `NULL` if empty or not defined
+ */
+char* getenv_nonempty(const char* var);
+
+
+/**
+ * Re-exec the server.
+ * This function only returns on failure.
+ * 
+ * @param  argc      The number of elements in `argv`
+ * @param  argv      The command line arguments
+ * @param  reexeced  Whether the server has previously been re-exec:ed
+ */
+void reexec_server(int argc, char** argv, int reexeced);
+
+
+#endif
+
diff --git a/src/mds-server.c b/src/mds-server.c
index 04f2124..8c9a863 100644
--- a/src/mds-server.c
+++ b/src/mds-server.c
@@ -23,6 +23,7 @@
 #include <libmdsserver/fd-table.h>
 #include <libmdsserver/mds-message.h>
 #include <libmdsserver/macros.h>
+#include <libmdsserver/util.h>
 
 #include <alloca.h>
 #include <signal.h>
@@ -398,10 +399,6 @@ int main(int argc_, char** argv_)
     pid_t pid = getpid();
     int reexec_fd;
     char shm_path[NAME_MAX + 1];
-    char readlink_buf[PATH_MAX];
-    ssize_t readlink_ptr;
-    char** reexec_args;
-    char** reexec_args_;
     
     /* Release resources. */
     pthread_mutex_destroy(&slave_mutex);
@@ -423,34 +420,15 @@ int main(int argc_, char** argv_)
     if (marshal_server(reexec_fd) < 0)
       goto reexec_fail;
     close(reexec_fd);
+    reexec_fd = -1;
     
     /* Re-exec the server. */
-    readlink_ptr = readlink(SELF_EXE, readlink_buf, (sizeof(readlink_buf) / sizeof(char)) - 1);
-    if (readlink_ptr < 0)
-      goto reexec_fail;
-    /* ‘readlink() does not append a null byte to buf.’ */
-    readlink_buf[readlink_ptr] = '\0';
-    reexec_args = alloca(((size_t)argc + 2) * sizeof(char*));
-    reexec_args_ = reexec_args;
-    if (reexec == 0)
-      {
-	*reexec_args_++ = *argv;
-	*reexec_args_ = strdup("--re-exec");
-	if (*reexec_args_)
-	  goto reexec_fail;
-	for (i = 1; i < argc; i++)
-	  reexec_args_[i] = argv[i];
-      }
-    else /* Don't let the --re-exec:s accumulate. */
-      *reexec_args_ = *argv;
-    for (i = 1; i < argc; i++)
-      reexec_args_[i] = argv[i];
-    reexec_args_[argc] = NULL;
-    execv(readlink_buf, reexec_args);
+    reexec_server(argc, argv, reexec);
     
   reexec_fail:
     perror(*argv);
-    close(reexec_fd);
+    if (reexec_fd >= 0)
+      close(reexec_fd);
     shm_unlink(shm_path);
     /* Returning non-zero is important, otherwise the server cannot
        be respawn if the re-exec fails. */
@@ -615,21 +593,6 @@ void* slave_loop(void* data)
 
 
 /**
- * Read an environment variable, but handle it as undefined if empty
- * 
- * @param   var  The environment variable's name
- * @return       The environment variable's value, `NULL` if empty or not defined
- */
-char* getenv_nonempty(const char* var)
-{
-  char* rc = getenv(var);
-  if ((rc == NULL) || (*rc == '\0'))
-    return NULL;
-  return rc;
-}
-
-
-/**
  * Exec into the mdsinitrc script
  * 
  * @param  args  The arguments to the child process
diff --git a/src/mds-server.h b/src/mds-server.h
index 67e97f6..609d7cf 100644
--- a/src/mds-server.h
+++ b/src/mds-server.h
@@ -67,14 +67,6 @@ typedef struct client
 void* slave_loop(void* data);
 
 /**
- * Read an environment variable, but handle it as undefined if empty
- * 
- * @param   var  The environment variable's name
- * @return       The environment variable's value, `NULL` if empty or not defined
- */
-char* getenv_nonempty(const char* var);
-
-/**
  * Exec into the mdsinitrc script
  * 
  * @param  args  The arguments to the child process