specifier: rework specifier calls to return proper error message

Previously the specifier calls could only indicate OOM by returning
NULL. With this change they will return negative errno-style error codes
like everything else.

5 files changed, 123 insertions, 77 deletions

diff --git a/src/shared/install-printf.c b/src/shared/install-printf.c
index 1157ea989b..1ee1243f4d 100644
--- a/src/shared/install-printf.c
+++ b/src/shared/install-printf.c
@@ -27,21 +27,35 @@
 #include "util.h"
 #include "install-printf.h"
 
-static char *specifier_prefix_and_instance(char specifier, void *data, void *userdata) {
+static int specifier_prefix_and_instance(char specifier, void *data, void *userdata, char **ret) {
         InstallInfo *i = userdata;
+        char *n;
+
         assert(i);
 
-        return unit_name_to_prefix_and_instance(i->name);
+        n = unit_name_to_prefix_and_instance(i->name);
+        if (!n)
+                return -ENOMEM;
+
+        *ret = n;
+        return 0;
 }
 
-static char *specifier_prefix(char specifier, void *data, void *userdata) {
+static int specifier_prefix(char specifier, void *data, void *userdata, char **ret) {
         InstallInfo *i = userdata;
+        char *n;
+
         assert(i);
 
-        return unit_name_to_prefix(i->name);
+        n = unit_name_to_prefix(i->name);
+        if (!n)
+                return -ENOMEM;
+
+        *ret = n;
+        return 0;
 }
 
-static char *specifier_instance(char specifier, void *data, void *userdata) {
+static int specifier_instance(char specifier, void *data, void *userdata, char **ret) {
         InstallInfo *i = userdata;
         char *instance;
         int r;
@@ -50,14 +64,19 @@ static char *specifier_instance(char specifier, void *data, void *userdata) {
 
         r = unit_name_to_instance(i->name, &instance);
         if (r < 0)
-                return NULL;
-        if (instance != NULL)
-                return instance;
-        else
-                return strdup("");
+                return r;
+
+        if (!instance) {
+                instance = strdup("");
+                if (!instance)
+                        return -ENOMEM;
+        }
+
+        *ret = instance;
+        return 0;
 }
 
-static char *specifier_user_name(char specifier, void *data, void *userdata) {
+static int specifier_user_name(char specifier, void *data, void *userdata, char **ret) {
         InstallInfo *i = userdata;
         const char *username;
         _cleanup_free_ char *tmp = NULL;
@@ -82,18 +101,20 @@ static char *specifier_user_name(char specifier, void *data, void *userdata) {
 
                 r = get_user_creds(&username, &uid, NULL, NULL, NULL);
                 if (r < 0)
-                        return NULL;
+                        return r;
 
                 if (asprintf(&printed, "%d", uid) < 0)
-                        return NULL;
+                        return -ENOMEM;
                 break;
         }}
 
-        return printed;
+
+        *ret = printed;
+        return 0;
 }
 
 
-char *install_full_printf(InstallInfo *i, const char *format) {
+int install_full_printf(InstallInfo *i, const char *format, char **ret) {
 
         /* This is similar to unit_full_printf() but does not support
          * anything path-related.
@@ -129,6 +150,7 @@ char *install_full_printf(InstallInfo *i, const char *format) {
 
         assert(i);
         assert(format);
+        assert(ret);
 
-        return specifier_printf(format, table, i);
+        return specifier_printf(format, table, i, ret);
 }
diff --git a/src/shared/install-printf.h b/src/shared/install-printf.h
index 46f5294d21..6ffa488b1b 100644
--- a/src/shared/install-printf.h
+++ b/src/shared/install-printf.h
@@ -22,4 +22,4 @@
 #pragma once
 
 #include "install.h"
-char *install_full_printf(InstallInfo *i, const char *format);
+int install_full_printf(InstallInfo *i, const char *format, char **ret);
diff --git a/src/shared/install.c b/src/shared/install.c
index 07e06c425f..9722ed4e1c 100644
--- a/src/shared/install.c
+++ b/src/shared/install.c
@@ -967,14 +967,15 @@ static int config_parse_user(const char *unit,
 
         InstallInfo *i = data;
         char* printed;
+        int r;
 
         assert(filename);
         assert(lvalue);
         assert(rvalue);
 
-        printed = install_full_printf(i, rvalue);
-        if (!printed)
-                return -ENOMEM;
+        r = install_full_printf(i, rvalue, &printed);
+        if (r < 0)
+                return r;
 
         free(i->user);
         i->user = printed;
@@ -1200,9 +1201,9 @@ static int install_info_symlink_alias(
         STRV_FOREACH(s, i->aliases) {
                 _cleanup_free_ char *alias_path = NULL, *dst = NULL;
 
-                dst = install_full_printf(i, *s);
-                if (!dst)
-                        return -ENOMEM;
+                q = install_full_printf(i, *s, &dst);
+                if (q < 0)
+                        return q;
 
                 alias_path = path_make_absolute(dst, config_path);
                 if (!alias_path)
@@ -1232,9 +1233,9 @@ static int install_info_symlink_wants(
         STRV_FOREACH(s, i->wanted_by) {
                 _cleanup_free_ char *path = NULL, *dst = NULL;
 
-                dst = install_full_printf(i, *s);
-                if (!dst)
-                        return -ENOMEM;
+                q = install_full_printf(i, *s, &dst);
+                if (q < 0)
+                        return q;
 
                 if (!unit_name_is_valid(dst, true)) {
                         r = -EINVAL;
@@ -1269,9 +1270,9 @@ static int install_info_symlink_requires(
         STRV_FOREACH(s, i->required_by) {
                 _cleanup_free_ char *path = NULL, *dst = NULL;
 
-                dst = install_full_printf(i, *s);
-                if (!dst)
-                        return -ENOMEM;
+                q = install_full_printf(i, *s, &dst);
+                if (q < 0)
+                        return q;
 
                 if (!unit_name_is_valid(dst, true)) {
                         r = -EINVAL;
diff --git a/src/shared/specifier.c b/src/shared/specifier.c
index bb8859fdfd..8fbf6db5df 100644
--- a/src/shared/specifier.c
+++ b/src/shared/specifier.c
@@ -32,21 +32,22 @@
  *
  */
 
-char *specifier_printf(const char *text, const Specifier table[], void *userdata) {
-        char *r, *t;
+int specifier_printf(const char *text, const Specifier table[], void *userdata, char **_ret) {
+        char *ret, *t;
         const char *f;
         bool percent = false;
         size_t l;
+        int r;
 
         assert(text);
         assert(table);
 
         l = strlen(text);
-        r = new(char, l+1);
-        if (!r)
-                return NULL;
+        ret = new(char, l+1);
+        if (!ret)
+                return -ENOMEM;
 
-        t = r;
+        t = ret;
 
         for (f = text; *f; f++, l--) {
 
@@ -61,32 +62,31 @@ char *specifier_printf(const char *text, const Specifier table[], void *userdata
                                                 break;
 
                                 if (i->lookup) {
-                                        char *n, *w;
+                                        _cleanup_free_ char *w = NULL;
+                                        char *n;
                                         size_t k, j;
 
-                                        w = i->lookup(i->specifier, i->data, userdata);
-                                        if (!w) {
-                                                free(r);
-                                                return NULL;
+                                        r = i->lookup(i->specifier, i->data, userdata, &w);
+                                        if (r < 0) {
+                                                free(ret);
+                                                return r;
                                         }
 
-                                        j = t - r;
+                                        j = t - ret;
                                         k = strlen(w);
 
                                         n = new(char, j + k + l + 1);
                                         if (!n) {
-                                                free(r);
-                                                free(w);
-                                                return NULL;
+                                                free(ret);
+                                                return -ENOMEM;
                                         }
 
-                                        memcpy(n, r, j);
+                                        memcpy(n, ret, j);
                                         memcpy(n + j, w, k);
 
-                                        free(r);
-                                        free(w);
+                                        free(ret);
 
-                                        r = n;
+                                        ret = n;
                                         t = n + j + k;
                                 } else {
                                         *(t++) = '%';
@@ -102,58 +102,81 @@ char *specifier_printf(const char *text, const Specifier table[], void *userdata
         }
 
         *t = 0;
-        return r;
+        *_ret = ret;
+        return 0;
 }
 
 /* Generic handler for simple string replacements */
 
-char* specifier_string(char specifier, void *data, void *userdata) {
-        return strdup(strempty(data));
+int specifier_string(char specifier, void *data, void *userdata, char **ret) {
+        char *n;
+
+        n = strdup(strempty(data));
+        if (!n)
+                return -ENOMEM;
+
+        *ret = n;
+        return 0;
 }
 
-char *specifier_machine_id(char specifier, void *data, void *userdata) {
+int specifier_machine_id(char specifier, void *data, void *userdata, char **ret) {
         sd_id128_t id;
-        char *buf;
+        char *n;
         int r;
 
         r = sd_id128_get_machine(&id);
         if (r < 0)
-                return NULL;
+                return r;
 
-        buf = new(char, 33);
-        if (!buf)
-                return NULL;
+        n = new(char, 33);
+        if (!n)
+                return -ENOMEM;
 
-        return sd_id128_to_string(id, buf);
+        *ret = sd_id128_to_string(id, n);
+        return 0;
 }
 
-char *specifier_boot_id(char specifier, void *data, void *userdata) {
+int specifier_boot_id(char specifier, void *data, void *userdata, char **ret) {
         sd_id128_t id;
-        char *buf;
+        char *n;
         int r;
 
         r = sd_id128_get_boot(&id);
         if (r < 0)
-                return NULL;
+                return r;
 
-        buf = new(char, 33);
-        if (!buf)
-                return NULL;
+        n = new(char, 33);
+        if (!n)
+                return -ENOMEM;
 
-        return sd_id128_to_string(id, buf);
+        *ret = sd_id128_to_string(id, n);
+        return 0;
 }
 
-char *specifier_host_name(char specifier, void *data, void *userdata) {
-        return gethostname_malloc();
+int specifier_host_name(char specifier, void *data, void *userdata, char **ret) {
+        char *n;
+
+        n = gethostname_malloc();
+        if (!n)
+                return -ENOMEM;
+
+        *ret = n;
+        return 0;
 }
 
-char *specifier_kernel_release(char specifier, void *data, void *userdata) {
+int specifier_kernel_release(char specifier, void *data, void *userdata, char **ret) {
         struct utsname uts;
+        char *n;
         int r;
 
         r = uname(&uts);
         if (r < 0)
-                return NULL;
+                return -errno;
+
+        n = strdup(uts.release);
+        if (!n)
+                return -ENOMEM;
 
-        return strdup(uts.release);
+        *ret = n;
+        return 0;
 }
diff --git a/src/shared/specifier.h b/src/shared/specifier.h
index d13e6406b6..fca206f665 100644
--- a/src/shared/specifier.h
+++ b/src/shared/specifier.h
@@ -21,7 +21,7 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
-typedef char* (*SpecifierCallback)(char specifier, void *data, void *userdata);
+typedef int (*SpecifierCallback)(char specifier, void *data, void *userdata, char **ret);
 
 typedef struct Specifier {
         const char specifier;
@@ -29,11 +29,11 @@ typedef struct Specifier {
         void *data;
 } Specifier;
 
-char *specifier_printf(const char *text, const Specifier table[], void *userdata);
+int specifier_printf(const char *text, const Specifier table[], void *userdata, char **ret);
 
-char *specifier_string(char specifier, void *data, void *userdata);
+int specifier_string(char specifier, void *data, void *userdata, char **ret);
 
-char *specifier_machine_id(char specifier, void *data, void *userdata);
-char *specifier_boot_id(char specifier, void *data, void *userdata);
-char *specifier_host_name(char specifier, void *data, void *userdata);
-char *specifier_kernel_release(char specifier, void *data, void *userdata);
+int specifier_machine_id(char specifier, void *data, void *userdata, char **ret);
+int specifier_boot_id(char specifier, void *data, void *userdata, char **ret);
+int specifier_host_name(char specifier, void *data, void *userdata, char **ret);
+int specifier_kernel_release(char specifier, void *data, void *userdata, char **ret);