[lxc-devel] [PATCH v2 2/3] lxccontainer.c: split up create_run_template() again

[TAMUKI Shoichi]

Split prepend_lxc_usernsexec() off from create_run_template() to allow
common use of the function.

Signed-off-by: TAMUKI Shoichi <tamuki at linet.gr.jp>
---
v2:
  - adjust to fit with the other patches.
  - correct misspelling in commit message.

 src/lxc/lxccontainer.c | 230 ++++++++++++++++++++++++++-----------------------
 1 file changed, 121 insertions(+), 109 deletions(-)

diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
index 07ffc08..4df1a4b 100644
--- a/src/lxc/lxccontainer.c
+++ b/src/lxc/lxccontainer.c
@@ -878,6 +878,8 @@ static char *lxcbasename(char *path)
 
 /* Require that callers free the returned string. */
 static char *figureout_rootfs(struct lxc_conf *conf);
+static char **prepend_lxc_usernsexec(char **tpath, struct lxc_conf *conf,
+		int nargs, char **newargv);
 
 static bool create_run_template(struct lxc_container *c, char *tpath, bool quiet,
 				char *const argv[])
@@ -964,115 +966,11 @@ static bool create_run_template(struct lxc_container *c, char *tpath, bool quiet
 			exit(1);
 		newargv[nargs - 1] = NULL;
 
-		/*
-		 * If we're running the template in a mapped userns, then
-		 * we prepend the template command with:
-		 * lxc-usernsexec <-m map1> ... <-m mapn> --
-		 * and we append "--mapped-uid x", where x is the mapped uid
-		 * for our geteuid()
-		 */
-		if (!lxc_list_empty(&conf->id_map)) {
-			int n2args = 1;
-			char txtuid[20];
-			char txtgid[20];
-			char **n2 = malloc(n2args * sizeof(*n2));
-			struct lxc_list *it;
-			struct id_map *map;
-
-			if (!n2) {
-				SYSERROR("out of memory");
-				exit(1);
-			}
-			newargv[0] = tpath;
-			tpath = "lxc-usernsexec";
-			n2[0] = "lxc-usernsexec";
-			lxc_list_for_each(it, &conf->id_map) {
-				map = it->elem;
-				n2args += 2;
-				n2 = realloc(n2, n2args * sizeof(char *));
-				if (!n2)
-					exit(1);
-				n2[n2args-2] = "-m";
-				n2[n2args-1] = malloc(200);
-				if (!n2[n2args-1])
-					exit(1);
-				ret = snprintf(n2[n2args-1], 200, "%c:%lu:%lu:%lu",
-					map->idtype == ID_TYPE_UID ? 'u' : 'g',
-					map->nsid, map->hostid, map->range);
-				if (ret < 0 || ret >= 200)
-					exit(1);
-			}
-			int hostid_mapped = mapped_hostid(geteuid(), conf, ID_TYPE_UID);
-			int extraargs = hostid_mapped >= 0 ? 1 : 3;
-			n2 = realloc(n2, (nargs + n2args + extraargs) * sizeof(char *));
-			if (!n2)
-				exit(1);
-			if (hostid_mapped < 0) {
-				hostid_mapped = find_unmapped_nsuid(conf, ID_TYPE_UID);
-				n2[n2args++] = "-m";
-				if (hostid_mapped < 0) {
-					ERROR("Could not find free uid to map");
-					exit(1);
-				}
-				n2[n2args++] = malloc(200);
-				if (!n2[n2args-1]) {
-					SYSERROR("out of memory");
-					exit(1);
-				}
-				ret = snprintf(n2[n2args-1], 200, "u:%d:%d:1",
-					hostid_mapped, geteuid());
-				if (ret < 0 || ret >= 200) {
-					ERROR("string too long");
-					exit(1);
-				}
-			}
-			int hostgid_mapped = mapped_hostid(getegid(), conf, ID_TYPE_GID);
-			extraargs = hostgid_mapped >= 0 ? 1 : 3;
-			n2 = realloc(n2, (nargs + n2args + extraargs) * sizeof(char *));
-			if (!n2)
-				exit(1);
-			if (hostgid_mapped < 0) {
-				hostgid_mapped = find_unmapped_nsuid(conf, ID_TYPE_GID);
-				n2[n2args++] = "-m";
-				if (hostgid_mapped < 0) {
-					ERROR("Could not find free uid to map");
-					exit(1);
-				}
-				n2[n2args++] = malloc(200);
-				if (!n2[n2args-1]) {
-					SYSERROR("out of memory");
-					exit(1);
-				}
-				ret = snprintf(n2[n2args-1], 200, "g:%d:%d:1",
-					hostgid_mapped, getegid());
-				if (ret < 0 || ret >= 200) {
-					ERROR("string too long");
-					exit(1);
-				}
-			}
-			n2[n2args++] = "--";
-			for (i = 0; i < nargs; i++)
-				n2[i + n2args] = newargv[i];
-			n2args += nargs;
-			// Finally add "--mapped-uid $uid" to tell template what to chown
-			// cached images to
-			n2args += 4;
-			n2 = realloc(n2, n2args * sizeof(char *));
-			if (!n2) {
-				SYSERROR("out of memory");
-				exit(1);
-			}
-			// note n2[n2args-1] is NULL
-			n2[n2args-5] = "--mapped-uid";
-			snprintf(txtuid, 20, "%d", hostid_mapped);
-			n2[n2args-4] = txtuid;
-			n2[n2args-3] = "--mapped-gid";
-			snprintf(txtgid, 20, "%d", hostgid_mapped);
-			n2[n2args-2] = txtgid;
-			n2[n2args-1] = NULL;
-			free(newargv);
-			newargv = n2;
-		}
+		/* prepend the template command with lxc-usernsexec */
+		if (!lxc_list_empty(&conf->id_map))
+			newargv = prepend_lxc_usernsexec(&tpath, conf,
+					nargs, newargv);
+
 		/* execute */
 		execvp(tpath, newargv);
 		SYSERROR("failed to execute template %s", tpath);
@@ -1141,6 +1039,120 @@ out:
 	return rootfs;
 }
 
+/*
+ * If we're running the template in a mapped userns, then
+ * we prepend the template command with:
+ * lxc-usernsexec <-m map1> ... <-m mapn> --
+ * and we append "--mapped-uid x", where x is the mapped uid
+ * for our geteuid()
+ */
+static char **prepend_lxc_usernsexec(char **tpath, struct lxc_conf *conf,
+		int nargs, char **newargv)
+{
+	int n2args = 1;
+	char txtuid[20];
+	char txtgid[20];
+	int i, ret;
+	char **n2 = malloc(n2args * sizeof(*n2));
+	struct lxc_list *it;
+	struct id_map *map;
+
+	if (!n2) {
+		SYSERROR("out of memory");
+		exit(1);
+	}
+	newargv[0] = *tpath;
+	*tpath = "lxc-usernsexec";
+	n2[0] = "lxc-usernsexec";
+	lxc_list_for_each(it, &conf->id_map) {
+		map = it->elem;
+		n2args += 2;
+		n2 = realloc(n2, n2args * sizeof(char *));
+		if (!n2)
+			exit(1);
+		n2[n2args-2] = "-m";
+		n2[n2args-1] = malloc(200);
+		if (!n2[n2args-1])
+			exit(1);
+		ret = snprintf(n2[n2args-1], 200, "%c:%lu:%lu:%lu",
+			map->idtype == ID_TYPE_UID ? 'u' : 'g',
+			map->nsid, map->hostid, map->range);
+		if (ret < 0 || ret >= 200)
+			exit(1);
+	}
+	int hostid_mapped = mapped_hostid(geteuid(), conf, ID_TYPE_UID);
+	int extraargs = hostid_mapped >= 0 ? 1 : 3;
+	n2 = realloc(n2, (nargs + n2args + extraargs) * sizeof(char *));
+	if (!n2)
+		exit(1);
+	if (hostid_mapped < 0) {
+		hostid_mapped = find_unmapped_nsuid(conf, ID_TYPE_UID);
+		n2[n2args++] = "-m";
+		if (hostid_mapped < 0) {
+			ERROR("Could not find free uid to map");
+			exit(1);
+		}
+		n2[n2args++] = malloc(200);
+		if (!n2[n2args-1]) {
+			SYSERROR("out of memory");
+			exit(1);
+		}
+		ret = snprintf(n2[n2args-1], 200, "u:%d:%d:1",
+			hostid_mapped, geteuid());
+		if (ret < 0 || ret >= 200) {
+			ERROR("string too long");
+			exit(1);
+		}
+	}
+	int hostgid_mapped = mapped_hostid(getegid(), conf, ID_TYPE_GID);
+	extraargs = hostgid_mapped >= 0 ? 1 : 3;
+	n2 = realloc(n2, (nargs + n2args + extraargs) * sizeof(char *));
+	if (!n2)
+		exit(1);
+	if (hostgid_mapped < 0) {
+		hostgid_mapped = find_unmapped_nsuid(conf, ID_TYPE_GID);
+		n2[n2args++] = "-m";
+		if (hostgid_mapped < 0) {
+			ERROR("Could not find free uid to map");
+			exit(1);
+		}
+		n2[n2args++] = malloc(200);
+		if (!n2[n2args-1]) {
+			SYSERROR("out of memory");
+			exit(1);
+		}
+		ret = snprintf(n2[n2args-1], 200, "g:%d:%d:1",
+			hostgid_mapped, getegid());
+		if (ret < 0 || ret >= 200) {
+			ERROR("string too long");
+			exit(1);
+		}
+	}
+	n2[n2args++] = "--";
+	for (i = 0; i < nargs; i++)
+		n2[i + n2args] = newargv[i];
+	n2args += nargs;
+	// Finally add "--mapped-uid $uid" to tell template what to chown
+	// cached images to
+	n2args += 4;
+	n2 = realloc(n2, n2args * sizeof(char *));
+	if (!n2) {
+		SYSERROR("out of memory");
+		exit(1);
+	}
+	// note n2[n2args-1] is NULL
+	n2[n2args-5] = "--mapped-uid";
+	snprintf(txtuid, 20, "%d", hostid_mapped);
+	n2[n2args-4] = txtuid;
+	n2[n2args-3] = "--mapped-gid";
+	snprintf(txtgid, 20, "%d", hostgid_mapped);
+	n2[n2args-2] = txtgid;
+	n2[n2args-1] = NULL;
+	free(newargv);
+	newargv = n2;
+	return newargv;
+}
+
 static bool prepend_lxc_header(char *path, const char *t, char *const argv[])
 {
 	long flen;
-- 
1.9.0