Document that meshlink_join() and meshlink_get_external_address() are blocking.

[meshlink] / src / conf.c

diff --git a/src/conf.c b/src/conf.c
index ad4b28b89708e0db5378ac5ec8ef460295c04dce..af8b0b0e20ba5e44a3c9953e5562577ef17eafd8 100644 (file)
--- a/src/conf.c
+++ b/src/conf.c
@@ -18,6 +18,7 @@
 */
 
 #include "system.h"
+#include <assert.h>
 
 #include "splay_tree.h"
 #include "connection.h"
@@ -333,30 +334,26 @@ bool write_config_file(const struct splay_tree_t *config_tree, const char *fname
 
        for splay_each(config_t, cnf, config_tree)
        {
-               if(fwrite(cnf->variable, sizeof(char), strlen(cnf->variable), fp) < strlen(cnf->variable)) {
-                       logger(NULL, MESHLINK_ERROR, "Cannot write to config file %s: %s", fname, strerror(errno));
-                       return false;
-               }
+               if(fwrite(cnf->variable, sizeof(char), strlen(cnf->variable), fp) < strlen(cnf->variable))
+                       goto error;
 
-               if(fwrite(" = ", sizeof(char), 3, fp) < 3) {
-                       logger(NULL, MESHLINK_ERROR, "Cannot write to config file %s: %s", fname, strerror(errno));
-                       return false;
-               }
+               if(fwrite(" = ", sizeof(char), 3, fp) < 3)
+                       goto error;
 
-               if(fwrite(cnf->value, sizeof(char), strlen(cnf->value), fp) < strlen(cnf->value)) {
-                       logger(NULL, MESHLINK_ERROR, "Cannot write to config file %s: %s", fname, strerror(errno));
-                       return false;
-               }
+               if(fwrite(cnf->value, sizeof(char), strlen(cnf->value), fp) < strlen(cnf->value))
+                       goto error;
 
-               if(fwrite("\n", sizeof(char), 1, fp) < 1) {
-                       logger(NULL, MESHLINK_ERROR, "Cannot write to config file %s: %s", fname, strerror(errno));
-                       return false;
-               }
+               if(fwrite("\n", sizeof(char), 1, fp) < 1)
+                       goto error;
        }
 
        fclose(fp);
-
        return true;
+
+error:
+       logger(NULL, MESHLINK_ERROR, "Cannot write to config file %s: %s", fname, strerror(errno));
+       fclose(fp);
+       return false;
 }
 
 bool read_server_config(meshlink_handle_t *mesh) {
@@ -391,18 +388,110 @@ bool write_host_config(struct meshlink_handle *mesh, const struct splay_tree_t *
        return write_config_file(config_tree, filename);
 }
 
-bool append_config_file(meshlink_handle_t *mesh, const char *name, const char *key, const char *value) {
+bool modify_config_file(struct meshlink_handle *mesh, const char *name, const char *key, const char *value, bool replace) {
+       assert(mesh && name && key && (replace || value));
+
        char filename[PATH_MAX];
-       snprintf(filename,PATH_MAX, "%s" SLASH "hosts" SLASH "%s", mesh->confbase, name);
+       char tmpname[PATH_MAX];
+       bool error = false;
 
-       FILE *fp = fopen(filename, "a");
+       snprintf(filename, sizeof filename, "%s" SLASH "hosts" SLASH "%s", mesh->confbase, name);
+       snprintf(tmpname, sizeof tmpname, "%s.tmp", filename);
 
-       if(!fp) {
+       FILE *fr = fopen(filename, "r");
+
+       if(!fr) {
                logger(mesh, MESHLINK_ERROR, "Cannot open config file %s: %s", filename, strerror(errno));
+               return false;
+       }
+
+       FILE *fw = fopen(tmpname, "w");
+
+       if(!fw) {
+               logger(mesh, MESHLINK_ERROR, "Cannot open temporary file %s: %s", tmpname, strerror(errno));
+               fclose(fr);
+               return false;
+       }
+
+       char buf[4096];
+       char *sep;
+       bool found = false;
+
+       while(readline(fr, buf, sizeof buf)) {
+               if(!*buf || *buf == '#')
+                       goto copy;
+
+               sep = strchr(buf, ' ');
+               if(!sep)
+                       goto copy;
+
+               *sep = 0;
+               if(strcmp(buf, key)) {
+                       *sep = ' ';
+                       goto copy;
+               }
+
+               if(!value) {
+                       found = true;
+                       continue;
+               }
+
+               // We found the key and the value. Keep one copy around.
+               if(sep[1] == '=' && sep[2] == ' ' && !strcmp(sep + 3, value)) {
+                       if(found)
+                               continue;
+                       found = true;
+               }
+
+               // We found the key but with a different value, delete it if wanted.
+               if(!found && replace)
+                       continue;
+
+               *sep = ' ';
+
+copy:
+               fprintf(fw, "%s\n", buf);
+       }
+
+       if(ferror(fr))
+               error = true;
+
+       fclose(fr);
+
+       // Add new key/value pair if necessary
+       if(!found && value)
+               fprintf(fw, "%s = %s\n", key, value);
+
+       if(ferror(fw))
+               error = true;
+
+       if(fclose(fw))
+               error = true;
+
+       // If any error occured during reading or writing, exit.
+       if(error) {
+               unlink(tmpname);
+               return false;
+       }
+
+       // Try to atomically replace the old config file with the new one.
+#ifdef HAVE_MINGW
+       char bakname[PATH_MAX];
+       snprintf(bakname, sizeof bakname, "%s.bak", filename);
+       if(rename(filename, bakname) || rename(tmpname, filename)) {
+               rename(bakname, filename);
+#else
+       if(rename(tmpname, filename)) {
+#endif
+               return false;
        } else {
-               fprintf(fp, "%s = %s\n", key, value);
-               fclose(fp);
+#ifdef HAVE_MINGW
+               unlink(bakname);
+#endif
+               return true;
        }
+}
 
-       return fp != NULL;
+bool append_config_file(meshlink_handle_t *mesh, const char *name, const char *key, const char *value) {
+       return modify_config_file(mesh, name, key, value, false);
 }