From: Lennart Poettering <lennart@poettering.net>
Date: Sun, 22 Apr 2012 12:48:46 +0000 (+0200)
Subject: util: unify getenv() logic for other PID
X-Git-Tag: v183~215
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ab94af9201496ea3aa59bbf2a01eb750fbd1c08a;p=systemd

util: unify getenv() logic for other PID
---

diff --git a/src/core/machine-id-setup.c b/src/core/machine-id-setup.c
index 9e84ac0c..636519c0 100644
--- a/src/core/machine-id-setup.c
+++ b/src/core/machine-id-setup.c
@@ -110,45 +110,22 @@ static int generate(char id[34]) {
         /* If that didn't work either, see if we are running in a
          * container, and a machine ID was passed in via
          * $container_uuid the way libvirt/LXC does it */
-
         r = detect_container(NULL);
         if (r > 0) {
-                FILE *f;
-
-                f = fopen("/proc/1/environ", "re");
-                if (f) {
-                        bool done = false;
-
-                        do {
-                                char line[LINE_MAX];
-                                unsigned i;
-
-                                for (i = 0; i < sizeof(line)-1; i++) {
-                                        int c;
-
-                                        c = getc(f);
-                                        if (_unlikely_(c == EOF)) {
-                                                done = true;
-                                                break;
-                                        } else if (c == 0)
-                                                break;
+                char *e;
 
-                                        line[i] = c;
-                                }
-                                line[i] = 0;
-
-                                if (startswith(line, "container_uuid=") &&
-                                    strlen(line + 15) >= 36) {
-                                        r = shorten_uuid(id, line + 15);
-                                        if (r >= 0) {
-                                                log_info("Initializing machine ID from container UUID");
-                                                return 0;
-                                        }
+                r = getenv_for_pid(1, "container_uuid", &e);
+                if (r > 0) {
+                        if (strlen(e) >= 36) {
+                                r = shorten_uuid(id, e);
+                                if (r >= 0) {
+                                        log_info("Initializing machine ID from container UUID");
+                                        free(e);
+                                        return 0;
                                 }
+                        }
 
-                        } while (!done);
-
-                        fclose(f);
+                        free(e);
                 }
         }
 
diff --git a/src/shared/util.c b/src/shared/util.c
index 317abb80..ba245628 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -6168,3 +6168,65 @@ int path_is_read_only_fs(const char *path) {
 
         return !!(st.f_flag & ST_RDONLY);
 }
+
+int getenv_for_pid(pid_t pid, const char *field, char **_value) {
+        char path[sizeof("/proc/")-1+10+sizeof("/environ")], *value = NULL;
+        int r;
+        FILE *f;
+        bool done = false;
+        size_t l;
+
+        assert(field);
+        assert(_value);
+
+        if (pid == 0)
+                pid = getpid();
+
+        snprintf(path, sizeof(path), "/proc/%lu/environ", (unsigned long) pid);
+        char_array_0(path);
+
+        f = fopen(path, "re");
+        if (!f)
+                return -errno;
+
+        l = strlen(field);
+        r = 0;
+
+        do {
+                char line[LINE_MAX];
+                unsigned i;
+
+                for (i = 0; i < sizeof(line)-1; i++) {
+                        int c;
+
+                        c = getc(f);
+                        if (_unlikely_(c == EOF)) {
+                                done = true;
+                                break;
+                        } else if (c == 0)
+                                break;
+
+                        line[i] = c;
+                }
+                line[i] = 0;
+
+                if (memcmp(line, field, l) == 0 && line[l] == '=') {
+                        value = strdup(line + l + 1);
+                        if (!value) {
+                                r = -ENOMEM;
+                                break;
+                        }
+
+                        r = 1;
+                        break;
+                }
+
+        } while (!done);
+
+        fclose(f);
+
+        if (r >= 0)
+                *_value = value;
+
+        return r;
+}
diff --git a/src/shared/util.h b/src/shared/util.h
index a26c1d9d..17ffd19f 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -540,4 +540,6 @@ int fork_agent(pid_t *pid, const int except[], unsigned n_except, const char *pa
 
 int setrlimit_closest(int resource, const struct rlimit *rlim);
 
+int getenv_for_pid(pid_t pid, const char *field, char **_value);
+
 #endif
diff --git a/src/shared/virt.c b/src/shared/virt.c
index b74c513d..6e447944 100644
--- a/src/shared/virt.c
+++ b/src/shared/virt.c
@@ -153,7 +153,8 @@ int detect_vm(const char **id) {
 }
 
 int detect_container(const char **id) {
-        FILE *f;
+        char *e = NULL;
+        int r;
 
         /* Unfortunately many of these operations require root access
          * in one way or another */
@@ -180,63 +181,29 @@ int detect_container(const char **id) {
                 return 1;
         }
 
-        f = fopen("/proc/1/environ", "re");
-        if (f) {
-                bool done = false;
-
-                do {
-                        char line[LINE_MAX];
-                        unsigned i;
-
-                        for (i = 0; i < sizeof(line)-1; i++) {
-                                int c;
-
-                                c = getc(f);
-                                if (_unlikely_(c == EOF)) {
-                                        done = true;
-                                        break;
-                                } else if (c == 0)
-                                        break;
-
-                                line[i] = c;
-                        }
-                        line[i] = 0;
-
-                        if (streq(line, "container=lxc")) {
-                                fclose(f);
-
-                                if (id)
-                                        *id = "lxc";
-                                return 1;
-
-                        } else if (streq(line, "container=lxc-libvirt")) {
-                                fclose(f);
-
-                                if (id)
-                                        *id = "lxc-libvirt";
-                                return 1;
+        r = getenv_for_pid(1, "container", &e);
+        if (r <= 0)
+                return r;
 
-                        } else if (streq(line, "container=systemd-nspawn")) {
-                                fclose(f);
-
-                                if (id)
-                                        *id = "systemd-nspawn";
-                                return 1;
-
-                        } else if (startswith(line, "container=")) {
-                                fclose(f);
-
-                                if (id)
-                                        *id = "other";
-                                return 1;
-                        }
-
-                } while (!done);
-
-                fclose(f);
+        /* We only recognize a selected few here, since we want to
+         * enforce a redacted namespace */
+        if (streq(e, "lxc")) {
+                if (id)
+                        *id = "lxc";
+        } else if (streq(e, "lxc-libvirt")) {
+                if (id)
+                        *id = "lxc-libvirt";
+        } else if (streq(e, "systemd-nspawn")) {
+                if (id)
+                        *id = "systemd-nspawn";
+        } else {
+                if (id)
+                        *id = "other";
         }
 
-        return 0;
+        free(e);
+
+        return r;
 }
 
 /* Returns a short identifier for the various VM/container implementations */