Merge pull request #14208 from poettering/json-homed-prepare

json bits from homed PR
2019-12-17 23:10:08 +09:00
parent 05de16766b 2d8143048b
commit 3267cb45e9
10 changed files with 1132 additions and 92 deletions
@@ -136,16 +136,21 @@ static int write_string_file_atomic(
        assert(fn);
        assert(line);

+        /* Note that we'd really like to use O_TMPFILE here, but can't really, since we want replacement
+         * semantics here, and O_TMPFILE can't offer that. i.e. rename() replaces but linkat() doesn't. */
+
        r = fopen_temporary(fn, &f, &p);
        if (r < 0)
                return r;

-        (void) fchmod_umask(fileno(f), 0644);
-
        r = write_string_stream_ts(f, line, flags, ts);
        if (r < 0)
                goto fail;

+        r = fchmod_umask(fileno(f), FLAGS_SET(flags, WRITE_STRING_FILE_MODE_0600) ? 0600 : 0644);
+        if (r < 0)
+                goto fail;
+
        if (rename(p, fn) < 0) {
                r = -errno;
                goto fail;
@@ -165,7 +170,7 @@ int write_string_file_ts(
                struct timespec *ts) {

        _cleanup_fclose_ FILE *f = NULL;
-        int q, r;
+        int q, r, fd;

        assert(fn);
        assert(line);
@@ -190,26 +195,20 @@ int write_string_file_ts(
        } else
                assert(!ts);

-        if (flags & WRITE_STRING_FILE_CREATE) {
-                r = fopen_unlocked(fn, "we", &f);
-                if (r < 0)
-                        goto fail;
-        } else {
-                int fd;
+        /* We manually build our own version of fopen(..., "we") that works without O_CREAT and with O_NOFOLLOW if needed. */
+        fd = open(fn, O_WRONLY|O_CLOEXEC|O_NOCTTY |
+                  (FLAGS_SET(flags, WRITE_STRING_FILE_NOFOLLOW) ? O_NOFOLLOW : 0) |
+                  (FLAGS_SET(flags, WRITE_STRING_FILE_CREATE) ? O_CREAT : 0),
+                  (FLAGS_SET(flags, WRITE_STRING_FILE_MODE_0600) ? 0600 : 0666));
+        if (fd < 0) {
+                r = -errno;
+                goto fail;
+        }

-                /* We manually build our own version of fopen(..., "we") that
-                 * works without O_CREAT */
-                fd = open(fn, O_WRONLY|O_CLOEXEC|O_NOCTTY | ((flags & WRITE_STRING_FILE_NOFOLLOW) ? O_NOFOLLOW : 0));
-                if (fd < 0) {
-                        r = -errno;
-                        goto fail;
-                }
-
-                r = fdopen_unlocked(fd, "w", &f);
-                if (r < 0) {
-                        safe_close(fd);
-                        goto fail;
-                }
+        r = fdopen_unlocked(fd, "w", &f);
+        if (r < 0) {
+                safe_close(fd);
+                goto fail;
        }

        if (flags & WRITE_STRING_FILE_DISABLE_BUFFER)
@@ -543,17 +542,19 @@ finalize:
        return r;
 }

-int read_full_file_full(const char *filename, ReadFullFileFlags flags, char **contents, size_t *size) {
+int read_full_file_full(int dir_fd, const char *filename, ReadFullFileFlags flags, char **contents, size_t *size) {
        _cleanup_fclose_ FILE *f = NULL;
        int r;

        assert(filename);
        assert(contents);

-        r = fopen_unlocked(filename, "re", &f);
+        r = xfopenat(dir_fd, filename, "re", 0, &f);
        if (r < 0)
                return r;

+        (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
+
        return read_full_stream_full(f, filename, flags, contents, size);
 }

@@ -680,6 +681,81 @@ DIR *xopendirat(int fd, const char *name, int flags) {
        return d;
 }

+static int mode_to_flags(const char *mode) {
+        const char *p;
+        int flags;
+
+        if ((p = startswith(mode, "r+")))
+                flags = O_RDWR;
+        else if ((p = startswith(mode, "r")))
+                flags = O_RDONLY;
+        else if ((p = startswith(mode, "w+")))
+                flags = O_RDWR|O_CREAT|O_TRUNC;
+        else if ((p = startswith(mode, "w")))
+                flags = O_WRONLY|O_CREAT|O_TRUNC;
+        else if ((p = startswith(mode, "a+")))
+                flags = O_RDWR|O_CREAT|O_APPEND;
+        else if ((p = startswith(mode, "a")))
+                flags = O_WRONLY|O_CREAT|O_APPEND;
+        else
+                return -EINVAL;
+
+        for (; *p != 0; p++) {
+
+                switch (*p) {
+
+                case 'e':
+                        flags |= O_CLOEXEC;
+                        break;
+
+                case 'x':
+                        flags |= O_EXCL;
+                        break;
+
+                case 'm':
+                        /* ignore this here, fdopen() might care later though */
+                        break;
+
+                case 'c': /* not sure what to do about this one */
+                default:
+                        return -EINVAL;
+                }
+        }
+
+        return flags;
+}
+
+int xfopenat(int dir_fd, const char *path, const char *mode, int flags, FILE **ret) {
+        FILE *f;
+
+        /* A combination of fopen() with openat() */
+
+        if (dir_fd == AT_FDCWD && flags == 0) {
+                f = fopen(path, mode);
+                if (!f)
+                        return -errno;
+        } else {
+                int fd, mode_flags;
+
+                mode_flags = mode_to_flags(mode);
+                if (mode_flags < 0)
+                        return mode_flags;
+
+                fd = openat(dir_fd, path, mode_flags | flags);
+                if (fd < 0)
+                        return -errno;
+
+                f = fdopen(fd, mode);
+                if (!f) {
+                        safe_close(fd);
+                        return -errno;
+                }
+        }
+
+        *ret = f;
+        return 0;
+}
+
 static int search_and_fopen_internal(const char *path, const char *mode, const char *root, char **search, FILE **_f) {
        char **i;

@@ -6,6 +6,7 @@
 #include <stddef.h>
 #include <stdio.h>
 #include <sys/stat.h>
+#include <sys/fcntl.h>
 #include <sys/types.h>

 #include "macro.h"
@@ -22,6 +23,7 @@ typedef enum {
        WRITE_STRING_FILE_DISABLE_BUFFER    = 1 << 5,
        WRITE_STRING_FILE_NOFOLLOW          = 1 << 6,
        WRITE_STRING_FILE_MKDIR_0755        = 1 << 7,
+        WRITE_STRING_FILE_MODE_0600         = 1 << 8,

        /* And before you wonder, why write_string_file_atomic_label_ts() is a separate function instead of just one
           more flag here: it's about linking: we don't want to pull -lselinux into all users of write_string_file()
@@ -52,9 +54,9 @@ static inline int write_string_file(const char *fn, const char *line, WriteStrin
 int write_string_filef(const char *fn, WriteStringFileFlags flags, const char *format, ...) _printf_(3, 4);

 int read_one_line_file(const char *filename, char **line);
-int read_full_file_full(const char *filename, ReadFullFileFlags flags, char **contents, size_t *size);
+int read_full_file_full(int dir_fd, const char *filename, ReadFullFileFlags flags, char **contents, size_t *size);
 static inline int read_full_file(const char *filename, char **contents, size_t *size) {
-        return read_full_file_full(filename, 0, contents, size);
+        return read_full_file_full(AT_FDCWD, filename, 0, contents, size);
 }
 int read_full_virtual_file(const char *filename, char **ret_contents, size_t *ret_size);
 int read_full_stream_full(FILE *f, const char *filename, ReadFullFileFlags flags, char **contents, size_t *size);
@@ -69,6 +71,7 @@ int executable_is_script(const char *path, char **interpreter);
 int get_proc_field(const char *filename, const char *pattern, const char *terminator, char **field);

 DIR *xopendirat(int dirfd, const char *name, int flags);
+int xfopenat(int dir_fd, const char *path, const char *mode, int flags, FILE **ret);

 int search_and_fopen(const char *path, const char *mode, const char *root, const char **search, FILE **_f);
 int search_and_fopen_nulstr(const char *path, const char *mode, const char *root, const char *search, FILE **_f);