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https://github.com/systemd/systemd
synced 2024-09-06 16:56:43 +00:00
Merge pull request #20676 from gogsbread/sysctl-minimize-sideeffect
sysctl: minimize side effects when running `systemd-sysctl`
This commit is contained in:
commit
41a978fdb1
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@ -148,6 +148,30 @@ int write_string_stream_ts(
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return -EBADF;
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}
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if (flags & WRITE_STRING_FILE_SUPPRESS_REDUNDANT_VIRTUAL) {
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_cleanup_free_ char *t = NULL;
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/* If value to be written is same as that of the existing value, then suppress the write. */
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if (fd < 0) {
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fd = fileno(f);
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if (fd < 0)
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return -EBADF;
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}
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/* Read an additional byte to detect cases where the prefix matches but the rest
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* doesn't. Also, 0 returned by read_virtual_file_fd() means the read was truncated and
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* it won't be equal to the new value. */
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if (read_virtual_file_fd(fd, strlen(line)+1, &t, NULL) > 0 &&
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streq_skip_trailing_chars(line, t, NEWLINE)) {
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log_debug("No change in value '%s', supressing write", line);
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return 0;
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}
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if (lseek(fd, 0, SEEK_SET) < 0)
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return -errno;
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}
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needs_nl = !(flags & WRITE_STRING_FILE_AVOID_NEWLINE) && !endswith(line, "\n");
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if (needs_nl && (flags & WRITE_STRING_FILE_DISABLE_BUFFER)) {
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@ -263,10 +287,11 @@ int write_string_file_ts(
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assert(!ts);
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/* We manually build our own version of fopen(..., "we") that works without O_CREAT and with O_NOFOLLOW if needed. */
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fd = open(fn, O_WRONLY|O_CLOEXEC|O_NOCTTY |
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fd = open(fn, O_CLOEXEC|O_NOCTTY |
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(FLAGS_SET(flags, WRITE_STRING_FILE_NOFOLLOW) ? O_NOFOLLOW : 0) |
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(FLAGS_SET(flags, WRITE_STRING_FILE_CREATE) ? O_CREAT : 0) |
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(FLAGS_SET(flags, WRITE_STRING_FILE_TRUNCATE) ? O_TRUNC : 0),
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(FLAGS_SET(flags, WRITE_STRING_FILE_TRUNCATE) ? O_TRUNC : 0) |
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(FLAGS_SET(flags, WRITE_STRING_FILE_SUPPRESS_REDUNDANT_VIRTUAL) ? O_RDWR : O_WRONLY),
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(FLAGS_SET(flags, WRITE_STRING_FILE_MODE_0600) ? 0600 : 0666));
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if (fd < 0) {
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r = -errno;
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@ -375,9 +400,8 @@ int verify_file(const char *fn, const char *blob, bool accept_extra_nl) {
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return 1;
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}
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int read_virtual_file(const char *filename, size_t max_size, char **ret_contents, size_t *ret_size) {
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int read_virtual_file_fd(int fd, size_t max_size, char **ret_contents, size_t *ret_size) {
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_cleanup_free_ char *buf = NULL;
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_cleanup_close_ int fd = -1;
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size_t n, size;
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int n_retries;
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bool truncated = false;
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@ -395,10 +419,7 @@ int read_virtual_file(const char *filename, size_t max_size, char **ret_contents
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* contents* may be returned. (Though the read is still done using one syscall.) Returns 0 on
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* partial success, 1 if untruncated contents were read. */
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fd = open(filename, O_RDONLY|O_NOCTTY|O_CLOEXEC);
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if (fd < 0)
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return -errno;
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assert(fd >= 0);
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assert(max_size <= READ_VIRTUAL_BYTES_MAX || max_size == SIZE_MAX);
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/* Limit the number of attempts to read the number of bytes returned by fstat(). */
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@ -434,8 +455,8 @@ int read_virtual_file(const char *filename, size_t max_size, char **ret_contents
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n_retries--;
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} else if (n_retries > 1) {
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/* Files in /proc are generally smaller than the page size so let's start with a page size
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* buffer from malloc and only use the max buffer on the final try. */
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/* Files in /proc are generally smaller than the page size so let's start with
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* a page size buffer from malloc and only use the max buffer on the final try. */
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size = MIN3(page_size() - 1, READ_VIRTUAL_BYTES_MAX, max_size);
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n_retries = 1;
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} else {
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@ -524,6 +545,18 @@ int read_virtual_file(const char *filename, size_t max_size, char **ret_contents
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return !truncated;
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}
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int read_virtual_file(const char *filename, size_t max_size, char **ret_contents, size_t *ret_size) {
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_cleanup_close_ int fd = -1;
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assert(filename);
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fd = open(filename, O_RDONLY | O_NOCTTY | O_CLOEXEC);
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if (fd < 0)
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return -errno;
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return read_virtual_file_fd(fd, max_size, ret_contents, ret_size);
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}
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int read_full_stream_full(
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FILE *f,
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const char *filename,
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@ -15,17 +15,18 @@
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#define LONG_LINE_MAX (1U*1024U*1024U)
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typedef enum {
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WRITE_STRING_FILE_CREATE = 1 << 0,
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WRITE_STRING_FILE_TRUNCATE = 1 << 1,
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WRITE_STRING_FILE_ATOMIC = 1 << 2,
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WRITE_STRING_FILE_AVOID_NEWLINE = 1 << 3,
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WRITE_STRING_FILE_VERIFY_ON_FAILURE = 1 << 4,
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WRITE_STRING_FILE_VERIFY_IGNORE_NEWLINE = 1 << 5,
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WRITE_STRING_FILE_SYNC = 1 << 6,
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WRITE_STRING_FILE_DISABLE_BUFFER = 1 << 7,
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WRITE_STRING_FILE_NOFOLLOW = 1 << 8,
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WRITE_STRING_FILE_MKDIR_0755 = 1 << 9,
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WRITE_STRING_FILE_MODE_0600 = 1 << 10,
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WRITE_STRING_FILE_CREATE = 1 << 0,
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WRITE_STRING_FILE_TRUNCATE = 1 << 1,
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WRITE_STRING_FILE_ATOMIC = 1 << 2,
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WRITE_STRING_FILE_AVOID_NEWLINE = 1 << 3,
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WRITE_STRING_FILE_VERIFY_ON_FAILURE = 1 << 4,
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WRITE_STRING_FILE_VERIFY_IGNORE_NEWLINE = 1 << 5,
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WRITE_STRING_FILE_SYNC = 1 << 6,
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WRITE_STRING_FILE_DISABLE_BUFFER = 1 << 7,
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WRITE_STRING_FILE_NOFOLLOW = 1 << 8,
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WRITE_STRING_FILE_MKDIR_0755 = 1 << 9,
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WRITE_STRING_FILE_MODE_0600 = 1 << 10,
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WRITE_STRING_FILE_SUPPRESS_REDUNDANT_VIRTUAL = 1 << 11,
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/* And before you wonder, why write_string_file_atomic_label_ts() is a separate function instead of just one
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more flag here: it's about linking: we don't want to pull -lselinux into all users of write_string_file()
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@ -67,6 +68,7 @@ static inline int read_full_file(const char *filename, char **ret_contents, size
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return read_full_file_full(AT_FDCWD, filename, UINT64_MAX, SIZE_MAX, 0, NULL, ret_contents, ret_size);
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}
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int read_virtual_file_fd(int fd, size_t max_size, char **ret_contents, size_t *ret_size);
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int read_virtual_file(const char *filename, size_t max_size, char **ret_contents, size_t *ret_size);
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static inline int read_full_virtual_file(const char *filename, char **ret_contents, size_t *ret_size) {
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return read_virtual_file(filename, SIZE_MAX, ret_contents, ret_size);
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@ -1146,3 +1146,19 @@ int string_contains_word_strv(const char *string, const char *separators, char *
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*ret_word = found;
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return !!found;
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}
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bool streq_skip_trailing_chars(const char *s1, const char *s2, const char *ok) {
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if (!s1 && !s2)
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return true;
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if (!s1 || !s2)
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return false;
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if (!ok)
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ok = WHITESPACE;
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for (; *s1 && *s2; s1++, s2++)
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if (*s1 != *s2)
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break;
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return in_charset(s1, ok) && in_charset(s2, ok);
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}
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@ -226,3 +226,5 @@ int string_contains_word_strv(const char *string, const char *separators, char *
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static inline int string_contains_word(const char *string, const char *separators, const char *word) {
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return string_contains_word_strv(string, separators, STRV_MAKE(word), NULL);
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}
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bool streq_skip_trailing_chars(const char *s1, const char *s2, const char *ok);
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@ -58,7 +58,7 @@ int sysctl_write(const char *property, const char *value) {
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log_debug("Setting '%s' to '%s'", p, value);
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return write_string_file(p, value, WRITE_STRING_FILE_VERIFY_ON_FAILURE | WRITE_STRING_FILE_DISABLE_BUFFER);
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return write_string_file(p, value, WRITE_STRING_FILE_VERIFY_ON_FAILURE | WRITE_STRING_FILE_DISABLE_BUFFER | WRITE_STRING_FILE_SUPPRESS_REDUNDANT_VIRTUAL);
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}
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int sysctl_writef(const char *property, const char *format, ...) {
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@ -1000,6 +1000,33 @@ static void test_strextendf(void) {
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assert_se(streq(p, "<77>,<99>,< 88>,<00001234>"));
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}
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static void test_streq_skip_trailing_chars(void) {
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log_info("/* %s */", __func__);
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/* NULL is WHITESPACE by default*/
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assert_se(streq_skip_trailing_chars("foo bar", "foo bar", NULL));
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assert_se(streq_skip_trailing_chars("foo", "foo", NULL));
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assert_se(streq_skip_trailing_chars("foo bar ", "foo bar", NULL));
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assert_se(streq_skip_trailing_chars("foo bar", "foo bar\t\t", NULL));
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assert_se(streq_skip_trailing_chars("foo bar ", "foo bar\t\t", NULL));
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assert_se(streq_skip_trailing_chars("foo\nbar", "foo\nbar", NULL));
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assert_se(streq_skip_trailing_chars("\t\tfoo bar", "\t\tfoo bar", NULL));
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assert_se(streq_skip_trailing_chars(" foo bar\t", " foo bar\n", NULL));
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assert_se(!streq_skip_trailing_chars("foobar", "foo bar", NULL));
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assert_se(!streq_skip_trailing_chars("foo\nbar", "foo\tbar", NULL));
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assert_se(!streq_skip_trailing_chars("\t\nfoo bar", "\t foo bar", NULL));
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assert_se(streq_skip_trailing_chars("foo bar ", "foo bar", WHITESPACE));
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assert_se(!streq_skip_trailing_chars("foo bar ", "foo bar", NEWLINE));
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assert_se(streq_skip_trailing_chars(NULL, NULL, NULL));
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assert_se(streq_skip_trailing_chars("", "", NULL));
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assert_se(!streq_skip_trailing_chars(NULL, "foo bar", NULL));
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assert_se(!streq_skip_trailing_chars("foo", NULL, NULL));
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assert_se(!streq_skip_trailing_chars("", "f", NULL));
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}
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int main(int argc, char *argv[]) {
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test_setup_logging(LOG_DEBUG);
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@ -1039,6 +1066,7 @@ int main(int argc, char *argv[]) {
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test_string_contains_word();
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test_strverscmp_improved();
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test_strextendf();
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test_streq_skip_trailing_chars();
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return 0;
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}
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