Merge pull request #18124 from ryncsn/initrd

initrd: add an env variable to accept non-ramfs rootfs

docs/ENVIRONMENT.md

@@ -52,9 +52,13 @@ All tools:
 * `$SYSTEMD_EFI_OPTIONS` — if set, used instead of the string in the
   SystemdOptions EFI variable. Analogous to `$SYSTEMD_PROC_CMDLINE`.
 
-* `$SYSTEMD_IN_INITRD` — takes a boolean. If set, overrides initrd detection.
-  This is useful for debugging and testing initrd-only programs in the main
-  system.
+* `$SYSTEMD_IN_INITRD=[auto|lenient|0|1]` — if set, specifies initrd detection
+  method. Defaults to `auto`. Behavior is defined as follows:
+  `auto`: Checks if `/etc/initrd-release` exists, and a temporary fs is mounted
+          on `/`. If both conditions meet, then it's in initrd.
+  `lenient`: Similiar to `auto`, but the rootfs check is skipped.
+  `0|1`: Simply overrides initrd detection. This is useful for debugging and
+         testing initrd-only programs in the main system.
 
 * `$SYSTEMD_BUS_TIMEOUT=SECS` — specifies the maximum time to wait for method call
   completion. If no time unit is specified, assumes seconds. The usual other units

man/systemd.exec.xml

@@ -2383,8 +2383,8 @@ SystemCallErrorNumber=EPERM</programlisting>
         to. Takes one of <option>inherit</option>, <option>null</option>, <option>tty</option>,
         <option>journal</option>, <option>kmsg</option>, <option>journal+console</option>,
         <option>kmsg+console</option>, <option>file:<replaceable>path</replaceable></option>,
-        <option>append:<replaceable>path</replaceable></option>, <option>socket</option> or
-        <option>fd:<replaceable>name</replaceable></option>.</para>
+        <option>append:<replaceable>path</replaceable></option>, <option>truncate:<replaceable>path</replaceable></option>,
+        <option>socket</option> or <option>fd:<replaceable>name</replaceable></option>.</para>
 
         <para><option>inherit</option> duplicates the file descriptor of standard input for standard output.</para>
 
@@ -2424,6 +2424,10 @@ SystemCallErrorNumber=EPERM</programlisting>
         <option>file:<replaceable>path</replaceable></option> above, but it opens the file in append mode.
         </para>
 
+        <para><option>truncate:<replaceable>path</replaceable></option> is similar to
+        <option>file:<replaceable>path</replaceable></option> above, but it truncates the file when opening it.
+        </para>
+
         <para><option>socket</option> connects standard output to a socket acquired via socket activation. The
         semantics are similar to the same option of <varname>StandardInput=</varname>, see above.</para>
 

src/basic/util.c

@@ -52,13 +52,14 @@ int prot_from_flags(int flags) {
 }
 
 bool in_initrd(void) {
-        struct statfs s;
         int r;
+        const char *e;
+        bool lenient = false;
 
         if (saved_in_initrd >= 0)
                 return saved_in_initrd;
 
-        /* We make two checks here:
+        /* We have two checks here:
          *
          * 1. the flag file /etc/initrd-release must exist
          * 2. the root file system must be a memory file system
@@ -66,18 +67,46 @@ bool in_initrd(void) {
          * The second check is extra paranoia, since misdetecting an
          * initrd can have bad consequences due the initrd
          * emptying when transititioning to the main systemd.
+         *
+         * If env var $SYSTEMD_IN_INITRD is not set or set to "auto",
+         * both checks are used. If it's set to "lenient", only check
+         * 1 is used. If set to a booleen value, then the boolean
+         * value is returned.
          */
 
-        r = getenv_bool_secure("SYSTEMD_IN_INITRD");
-        if (r < 0 && r != -ENXIO)
-                log_debug_errno(r, "Failed to parse $SYSTEMD_IN_INITRD, ignoring: %m");
+        e = secure_getenv("SYSTEMD_IN_INITRD");
+        if (e) {
+                if (streq(e, "lenient"))
+                        lenient = true;
+                else if (!streq(e, "auto")) {
+                        r = parse_boolean(e);
+                        if (r >= 0) {
+                                saved_in_initrd = r > 0;
+                                return saved_in_initrd;
+                        }
+                        log_debug_errno(r, "Failed to parse $SYSTEMD_IN_INITRD, ignoring: %m");
+                }
+        }
+
+        if (!lenient) {
+                r = path_is_temporary_fs("/");
+                if (r < 0)
+                        log_debug_errno(r, "Couldn't determine if / is a temporary file system: %m");
 
-        if (r >= 0)
                 saved_in_initrd = r > 0;
-        else
-                saved_in_initrd = access("/etc/initrd-release", F_OK) >= 0 &&
-                                  statfs("/", &s) >= 0 &&
-                                  is_temporary_fs(&s);
+        }
+
+        r = access("/etc/initrd-release", F_OK);
+        if (r >= 0) {
+                if (saved_in_initrd == 0)
+                        log_debug("/etc/initrd-release exists, but it's not an initrd.");
+                else
+                        saved_in_initrd = 1;
+        } else {
+                if (errno != ENOENT)
+                        log_debug_errno(errno, "Failed to test if /etc/initrd-release exists: %m");
+                saved_in_initrd = 0;
+        }
 
         return saved_in_initrd;
 }

src/core/dbus-execute.c

@@ -2727,8 +2727,8 @@ int bus_exec_context_set_transient_property(
 
         } else if (STR_IN_SET(name,
                               "StandardInputFile",
-                              "StandardOutputFile", "StandardOutputFileToAppend",
-                              "StandardErrorFile", "StandardErrorFileToAppend")) {
+                              "StandardOutputFile", "StandardOutputFileToAppend", "StandardOutputFileToTruncate",
+                              "StandardErrorFile", "StandardErrorFileToAppend", "StandardErrorFileToTruncate")) {
                 const char *s;
 
                 r = sd_bus_message_read(message, "s", &s);
@@ -2752,7 +2752,7 @@ int bus_exec_context_set_transient_property(
                                 c->std_input = EXEC_INPUT_FILE;
                                 unit_write_settingf(u, flags|UNIT_ESCAPE_SPECIFIERS, name, "StandardInput=file:%s", s);
 
-                        } else if (STR_IN_SET(name, "StandardOutputFile", "StandardOutputFileToAppend")) {
+                        } else if (STR_IN_SET(name, "StandardOutputFile", "StandardOutputFileToAppend", "StandardOutputFileToTruncate")) {
                                 r = free_and_strdup(&c->stdio_file[STDOUT_FILENO], empty_to_null(s));
                                 if (r < 0)
                                         return r;
@@ -2760,13 +2760,16 @@ int bus_exec_context_set_transient_property(
                                 if (streq(name, "StandardOutputFile")) {
                                         c->std_output = EXEC_OUTPUT_FILE;
                                         unit_write_settingf(u, flags|UNIT_ESCAPE_SPECIFIERS, name, "StandardOutput=file:%s", s);
-                                } else {
-                                        assert(streq(name, "StandardOutputFileToAppend"));
+                                } else if (streq(name, "StandardOutputFileToAppend")) {
                                         c->std_output = EXEC_OUTPUT_FILE_APPEND;
                                         unit_write_settingf(u, flags|UNIT_ESCAPE_SPECIFIERS, name, "StandardOutput=append:%s", s);
+                                } else {
+                                        assert(streq(name, "StandardOutputFileToTruncate"));
+                                        c->std_output = EXEC_OUTPUT_FILE_TRUNCATE;
+                                        unit_write_settingf(u, flags|UNIT_ESCAPE_SPECIFIERS, name, "StandardOutput=truncate:%s", s);
                                 }
                         } else {
-                                assert(STR_IN_SET(name, "StandardErrorFile", "StandardErrorFileToAppend"));
+                                assert(STR_IN_SET(name, "StandardErrorFile", "StandardErrorFileToAppend", "StandardErrorFileToTruncate"));
 
                                 r = free_and_strdup(&c->stdio_file[STDERR_FILENO], empty_to_null(s));
                                 if (r < 0)
@@ -2775,10 +2778,13 @@ int bus_exec_context_set_transient_property(
                                 if (streq(name, "StandardErrorFile")) {
                                         c->std_error = EXEC_OUTPUT_FILE;
                                         unit_write_settingf(u, flags|UNIT_ESCAPE_SPECIFIERS, name, "StandardError=file:%s", s);
-                                } else {
-                                        assert(streq(name, "StandardErrorFileToAppend"));
+                                } else if (streq(name, "StandardErrorFileToAppend")) {
                                         c->std_error = EXEC_OUTPUT_FILE_APPEND;
                                         unit_write_settingf(u, flags|UNIT_ESCAPE_SPECIFIERS, name, "StandardError=append:%s", s);
+                                } else {
+                                        assert(streq(name, "StandardErrorFileToTruncate"));
+                                        c->std_error = EXEC_OUTPUT_FILE_TRUNCATE;
+                                        unit_write_settingf(u, flags|UNIT_ESCAPE_SPECIFIERS, name, "StandardError=truncate:%s", s);
                                 }
                         }
                 }

src/core/execute.c

@@ -562,7 +562,7 @@ static bool can_inherit_stderr_from_stdout(
         if (e == EXEC_OUTPUT_NAMED_FD)
                 return streq_ptr(context->stdio_fdname[STDOUT_FILENO], context->stdio_fdname[STDERR_FILENO]);
 
-        if (IN_SET(e, EXEC_OUTPUT_FILE, EXEC_OUTPUT_FILE_APPEND))
+        if (IN_SET(e, EXEC_OUTPUT_FILE, EXEC_OUTPUT_FILE_APPEND, EXEC_OUTPUT_FILE_TRUNCATE))
                 return streq_ptr(context->stdio_file[STDOUT_FILENO], context->stdio_file[STDERR_FILENO]);
 
         return true;
@@ -698,7 +698,8 @@ static int setup_output(
                 return dup2(named_iofds[fileno], fileno) < 0 ? -errno : fileno;
 
         case EXEC_OUTPUT_FILE:
-        case EXEC_OUTPUT_FILE_APPEND: {
+        case EXEC_OUTPUT_FILE_APPEND:
+        case EXEC_OUTPUT_FILE_TRUNCATE: {
                 bool rw;
                 int fd, flags;
 
@@ -713,6 +714,8 @@ static int setup_output(
                 flags = O_WRONLY;
                 if (o == EXEC_OUTPUT_FILE_APPEND)
                         flags |= O_APPEND;
+                else if (o == EXEC_OUTPUT_FILE_TRUNCATE)
+                        flags |= O_TRUNC;
 
                 fd = acquire_path(context->stdio_file[fileno], flags, 0666 & ~context->umask);
                 if (fd < 0)
@@ -5357,10 +5360,14 @@ void exec_context_dump(const ExecContext *c, FILE* f, const char *prefix) {
                 fprintf(f, "%sStandardOutputFile: %s\n", prefix, c->stdio_file[STDOUT_FILENO]);
         if (c->std_output == EXEC_OUTPUT_FILE_APPEND)
                 fprintf(f, "%sStandardOutputFileToAppend: %s\n", prefix, c->stdio_file[STDOUT_FILENO]);
+        if (c->std_output == EXEC_OUTPUT_FILE_TRUNCATE)
+                fprintf(f, "%sStandardOutputFileToTruncate: %s\n", prefix, c->stdio_file[STDOUT_FILENO]);
         if (c->std_error == EXEC_OUTPUT_FILE)
                 fprintf(f, "%sStandardErrorFile: %s\n", prefix, c->stdio_file[STDERR_FILENO]);
         if (c->std_error == EXEC_OUTPUT_FILE_APPEND)
                 fprintf(f, "%sStandardErrorFileToAppend: %s\n", prefix, c->stdio_file[STDERR_FILENO]);
+        if (c->std_error == EXEC_OUTPUT_FILE_TRUNCATE)
+                fprintf(f, "%sStandardErrorFileToTruncate: %s\n", prefix, c->stdio_file[STDERR_FILENO]);
 
         if (c->tty_path)
                 fprintf(f,
@@ -6449,6 +6456,7 @@ static const char* const exec_output_table[_EXEC_OUTPUT_MAX] = {
         [EXEC_OUTPUT_NAMED_FD] = "fd",
         [EXEC_OUTPUT_FILE] = "file",
         [EXEC_OUTPUT_FILE_APPEND] = "append",
+        [EXEC_OUTPUT_FILE_TRUNCATE] = "truncate",
 };
 
 DEFINE_STRING_TABLE_LOOKUP(exec_output, ExecOutput);

src/core/execute.h

@@ -61,6 +61,7 @@ typedef enum ExecOutput {
         EXEC_OUTPUT_NAMED_FD,
         EXEC_OUTPUT_FILE,
         EXEC_OUTPUT_FILE_APPEND,
+        EXEC_OUTPUT_FILE_TRUNCATE,
         _EXEC_OUTPUT_MAX,
         _EXEC_OUTPUT_INVALID = -1
 } ExecOutput;

src/core/load-fragment.c

@@ -1202,6 +1202,20 @@ int config_parse_exec_output(
                         return 0;
 
                 eo = EXEC_OUTPUT_FILE_APPEND;
+
+        } else if ((n = startswith(rvalue, "truncate:"))) {
+
+                r = unit_full_printf(u, n, &resolved);
+                if (r < 0) {
+                        log_syntax(unit, LOG_WARNING, filename, line, r, "Failed to resolve unit specifiers in %s, ignoring: %m", n);
+                        return 0;
+                }
+
+                r = path_simplify_and_warn(resolved, PATH_CHECK_ABSOLUTE | PATH_CHECK_FATAL, unit, filename, line, lvalue);
+                if (r < 0)
+                        return 0;
+
+                eo = EXEC_OUTPUT_FILE_TRUNCATE;
         } else {
                 eo = exec_output_from_string(rvalue);
                 if (eo < 0) {
@@ -5761,8 +5775,8 @@ int config_parse_output_restricted(
                         return 0;
                 }
 
-                if (IN_SET(t, EXEC_OUTPUT_SOCKET, EXEC_OUTPUT_NAMED_FD, EXEC_OUTPUT_FILE, EXEC_OUTPUT_FILE_APPEND)) {
-                        log_syntax(unit, LOG_WARNING, filename, line, 0, "Standard output types socket, fd:, file:, append: are not supported as defaults, ignoring: %s", rvalue);
+                if (IN_SET(t, EXEC_OUTPUT_SOCKET, EXEC_OUTPUT_NAMED_FD, EXEC_OUTPUT_FILE, EXEC_OUTPUT_FILE_APPEND, EXEC_OUTPUT_FILE_TRUNCATE)) {
+                        log_syntax(unit, LOG_WARNING, filename, line, 0, "Standard output types socket, fd:, file:, append:, truncate: are not supported as defaults, ignoring: %s", rvalue);
                         return 0;
                 }
         }

src/shared/bus-unit-util.c

@@ -1144,6 +1144,9 @@ static int bus_append_execute_property(sd_bus_message *m, const char *field, con
                 } else if ((n = startswith(eq, "append:"))) {
                         appended = strjoina(field, "FileToAppend");
                         r = sd_bus_message_append(m, "(sv)", appended, "s", n);
+                } else if ((n = startswith(eq, "truncate:"))) {
+                        appended = strjoina(field, "FileToTruncate");
+                        r = sd_bus_message_append(m, "(sv)", appended, "s", n);
                 } else
                         r = sd_bus_message_append(m, "(sv)", field, "s", eq);
                 if (r < 0)

src/test/test-execute.c

@@ -811,6 +811,10 @@ static void test_exec_standardoutput_append(Manager *m) {
         test(m, "exec-standardoutput-append.service", 0, CLD_EXITED);
 }
 
+static void test_exec_standardoutput_truncate(Manager *m) {
+        test(m, "exec-standardoutput-truncate.service", 0, CLD_EXITED);
+}
+
 static void test_exec_condition(Manager *m) {
         test_service(m, "exec-condition-failed.service", SERVICE_FAILURE_EXIT_CODE);
         test_service(m, "exec-condition-skip.service", SERVICE_SKIP_CONDITION);
@@ -876,6 +880,7 @@ int main(int argc, char *argv[]) {
                 entry(test_exec_standardinput),
                 entry(test_exec_standardoutput),
                 entry(test_exec_standardoutput_append),
+                entry(test_exec_standardoutput_truncate),
                 entry(test_exec_supplementarygroups),
                 entry(test_exec_systemcallerrornumber),
                 entry(test_exec_systemcallfilter),

test/test-execute/exec-standardoutput-truncate.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=Test for StandardOutput=truncate:
+
+[Service]
+ExecStartPre=sh -c 'printf "hello\n" > /tmp/test-exec-standardoutput-output'
+ExecStartPre=sh -c 'printf "hi\n" > /tmp/test-exec-standardoutput-expected'
+StandardInput=data
+StandardInputText=hi
+StandardOutput=truncate:/tmp/test-exec-standardoutput-output
+StandardError=null
+ExecStart=cat
+ExecStartPost=cmp /tmp/test-exec-standardoutput-output /tmp/test-exec-standardoutput-expected
+Type=oneshot

test/units/testsuite-27.sh

@@ -43,6 +43,18 @@ a
 c
 EOF
 
+systemd-run --wait --unit=test27-four \
+            -p StandardOutput=truncate:/tmp/stdout \
+            -p StandardError=truncate:/tmp/stderr \
+            -p Type=exec \
+            sh -c 'echo a ; echo b >&2'
+cmp /tmp/stdout <<EOF
+a
+EOF
+cmp /tmp/stderr <<EOF
+b
+EOF
+
 systemd-analyze log-level info
 
 echo OK >/testok