Prevent channel buffer allocation larger than memory

[lttng-tools.git] / src / bin / lttng / conf.c

diff --git a/src/bin/lttng/conf.c b/src/bin/lttng/conf.c
index c1bfcfd45b8d87eacfae6d3be878033121ee85cc..6fc3e605128181e8615c72976129c4c56d70e7da 100644 (file)
--- a/src/bin/lttng/conf.c
+++ b/src/bin/lttng/conf.c
@@ -15,7 +15,7 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#define _GNU_SOURCE
+#define _LGPL_SOURCE
 #include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -23,8 +23,10 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
+#include <errno.h>
 
-#include <common/error.h>
+#include <common/common.h>
+#include <common/utils.h>
 
 #include "conf.h"
 
@@ -40,6 +42,7 @@ char *config_get_file_path(char *path)
        ret = asprintf(&file_path, "%s/%s", path, CONFIG_FILENAME);
        if (ret < 0) {
                ERR("Fail allocating config file path");
+               file_path = NULL;
        }
 
        return file_path;
@@ -121,14 +124,6 @@ end:
        return ret;
 }
 
-/*
- * Returns the HOME directory path. Caller MUST NOT free(3) the return pointer.
- */
-char *config_get_default_path(void)
-{
-       return getenv("HOME");
-}
-
 /*
  * Destroys directory config and file config.
  */
@@ -149,7 +144,7 @@ void config_destroy(char *path)
        DBG("Removing %s\n", config_path);
        ret = remove(config_path);
        if (ret < 0) {
-               perror("remove config file");
+               PERROR("remove config file");
        }
 end:
        free(config_path);
@@ -160,7 +155,7 @@ end:
  */
 void config_destroy_default(void)
 {
-       char *path = config_get_default_path();
+       char *path = utils_get_home_dir();
        if (path == NULL) {
                return;
        }
@@ -182,32 +177,34 @@ int config_exists(const char *path)
        return S_ISREG(info.st_mode) || S_ISDIR(info.st_mode);
 }
 
-/*
- * Returns the session name from the config file.
- * The caller is responsible for freeing the returned string.
- * On error, NULL is returned.
- */
-char *config_read_session_name(char *path)
+static
+int _config_read_session_name(char *path, char **name)
 {
-       int ret;
+       int ret = 0;
        FILE *fp;
        char var[NAME_MAX], *session_name;
 
-       session_name = malloc(NAME_MAX);
+#if (NAME_MAX == 255)
+#define NAME_MAX_SCANF_IS_A_BROKEN_API "254"
+#endif
+
+       session_name = zmalloc(NAME_MAX);
        if (session_name == NULL) {
+               ret = -ENOMEM;
                ERR("Out of memory");
                goto error;
        }
 
        fp = open_config(path, "r");
        if (fp == NULL) {
-               ERR("Can't find valid lttng config %s/.lttngrc", path);
-               MSG("Did you create a session? (lttng create <my_session>)");
+               ret = -ENOENT;
                goto error;
        }
 
        while (!feof(fp)) {
-               if ((ret = fscanf(fp, "%[^'=']=%s\n", var, session_name)) != 2) {
+               if ((ret = fscanf(fp, "%" NAME_MAX_SCANF_IS_A_BROKEN_API
+                               "[^'=']=%" NAME_MAX_SCANF_IS_A_BROKEN_API "s\n",
+                               var, session_name)) != 2) {
                        if (ret == -1) {
                                ERR("Missing session=NAME in config file.");
                                goto error_close;
@@ -221,21 +218,54 @@ char *config_read_session_name(char *path)
        }
 
 error_close:
-       ret = fclose(fp);
-       if (ret < 0) {
+       if (fclose(fp) < 0) {
                PERROR("close config read session name");
        }
-
 error:
-       return NULL;
-
+       free(session_name);
+       return ret;
 found:
-       ret = fclose(fp);
-       if (ret < 0) {
+       *name = session_name;
+       if (fclose(fp) < 0) {
                PERROR("close config read session name found");
        }
-       return session_name;
+       return ret;
+}
+
+/*
+ * Returns the session name from the config file.
+ *
+ * The caller is responsible for freeing the returned string.
+ * On error, NULL is returned.
+ */
+char *config_read_session_name(char *path)
+{
+       int ret;
+       char *name = NULL;
+
+       ret = _config_read_session_name(path, &name);
+       if (ret == -ENOENT) {
+               const char *home_dir = utils_get_home_dir();
+
+               ERR("Can't find valid lttng config %s/.lttngrc", home_dir);
+               MSG("Did you create a session? (lttng create <my_session>)");
+       }
+
+       return name;
+}
+
+/*
+ * Returns the session name from the config file. (no warnings/errors emitted)
+ *
+ * The caller is responsible for freeing the returned string.
+ * On error, NULL is returned.
+ */
+char *config_read_session_name_quiet(char *path)
+{
+       char *name = NULL;
 
+       (void) _config_read_session_name(path, &name);
+       return name;
 }
 
 /*
@@ -246,14 +276,16 @@ found:
 int config_add_session_name(char *path, char *name)
 {
        int ret;
-       char session_name[NAME_MAX];
+       char *attr = "session=";
+       /* Max name len accepted plus attribute's len and the NULL byte. */
+       char session_name[NAME_MAX + strlen(attr) + 1];
 
        /*
         * With GNU C <  2.1, snprintf returns -1 if the target buffer is too small;
         * With GNU C >= 2.1, snprintf returns the required size (excluding closing null)
         */
-       ret = snprintf(session_name, NAME_MAX, "session=%s\n", name);
-       if ((ret < 0) || (ret >= NAME_MAX)) {
+       ret = snprintf(session_name, sizeof(session_name), "%s%s\n", attr, name);
+       if (ret < 0) {
                ret = -1;
                goto error;
        }
@@ -272,7 +304,7 @@ int config_init(char *session_name)
        int ret;
        char *path;
 
-       path = config_get_default_path();
+       path = utils_get_home_dir();
        if (path == NULL) {
                ret = -1;
                goto error;