summaryrefslogtreecommitdiffstats
path: root/src/basic/fileio.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/basic/fileio.c')
-rw-r--r--src/basic/fileio.c822
1 files changed, 822 insertions, 0 deletions
diff --git a/src/basic/fileio.c b/src/basic/fileio.c
new file mode 100644
index 0000000..e18b842
--- /dev/null
+++ b/src/basic/fileio.c
@@ -0,0 +1,822 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdarg.h>
+#include <stdint.h>
+#include <stdio_ext.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "fs-util.h"
+#include "log.h"
+#include "macro.h"
+#include "missing.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "stdio-util.h"
+#include "string-util.h"
+#include "tmpfile-util.h"
+
+#define READ_FULL_BYTES_MAX (4U*1024U*1024U)
+
+int write_string_stream_ts(
+ FILE *f,
+ const char *line,
+ WriteStringFileFlags flags,
+ struct timespec *ts) {
+
+ bool needs_nl;
+ int r;
+
+ assert(f);
+ assert(line);
+
+ if (ferror(f))
+ return -EIO;
+
+ needs_nl = !(flags & WRITE_STRING_FILE_AVOID_NEWLINE) && !endswith(line, "\n");
+
+ if (needs_nl && (flags & WRITE_STRING_FILE_DISABLE_BUFFER)) {
+ /* If STDIO buffering was disabled, then let's append the newline character to the string itself, so
+ * that the write goes out in one go, instead of two */
+
+ line = strjoina(line, "\n");
+ needs_nl = false;
+ }
+
+ if (fputs(line, f) == EOF)
+ return -errno;
+
+ if (needs_nl)
+ if (fputc('\n', f) == EOF)
+ return -errno;
+
+ if (flags & WRITE_STRING_FILE_SYNC)
+ r = fflush_sync_and_check(f);
+ else
+ r = fflush_and_check(f);
+ if (r < 0)
+ return r;
+
+ if (ts) {
+ struct timespec twice[2] = {*ts, *ts};
+
+ if (futimens(fileno(f), twice) < 0)
+ return -errno;
+ }
+
+ return 0;
+}
+
+static int write_string_file_atomic(
+ const char *fn,
+ const char *line,
+ WriteStringFileFlags flags,
+ struct timespec *ts) {
+
+ _cleanup_fclose_ FILE *f = NULL;
+ _cleanup_free_ char *p = NULL;
+ int r;
+
+ assert(fn);
+ assert(line);
+
+ r = fopen_temporary(fn, &f, &p);
+ if (r < 0)
+ return r;
+
+ (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
+ (void) fchmod_umask(fileno(f), 0644);
+
+ r = write_string_stream_ts(f, line, flags, ts);
+ if (r < 0)
+ goto fail;
+
+ if (rename(p, fn) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ return 0;
+
+fail:
+ (void) unlink(p);
+ return r;
+}
+
+int write_string_file_ts(
+ const char *fn,
+ const char *line,
+ WriteStringFileFlags flags,
+ struct timespec *ts) {
+
+ _cleanup_fclose_ FILE *f = NULL;
+ int q, r;
+
+ assert(fn);
+ assert(line);
+
+ /* We don't know how to verify whether the file contents was already on-disk. */
+ assert(!((flags & WRITE_STRING_FILE_VERIFY_ON_FAILURE) && (flags & WRITE_STRING_FILE_SYNC)));
+
+ if (flags & WRITE_STRING_FILE_ATOMIC) {
+ assert(flags & WRITE_STRING_FILE_CREATE);
+
+ r = write_string_file_atomic(fn, line, flags, ts);
+ if (r < 0)
+ goto fail;
+
+ return r;
+ } else
+ assert(!ts);
+
+ if (flags & WRITE_STRING_FILE_CREATE) {
+ f = fopen(fn, "we");
+ if (!f) {
+ r = -errno;
+ goto fail;
+ }
+ } else {
+ int fd;
+
+ /* 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;
+ }
+
+ f = fdopen(fd, "w");
+ if (!f) {
+ r = -errno;
+ safe_close(fd);
+ goto fail;
+ }
+ }
+
+ (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
+
+ if (flags & WRITE_STRING_FILE_DISABLE_BUFFER)
+ setvbuf(f, NULL, _IONBF, 0);
+
+ r = write_string_stream_ts(f, line, flags, ts);
+ if (r < 0)
+ goto fail;
+
+ return 0;
+
+fail:
+ if (!(flags & WRITE_STRING_FILE_VERIFY_ON_FAILURE))
+ return r;
+
+ f = safe_fclose(f);
+
+ /* OK, the operation failed, but let's see if the right
+ * contents in place already. If so, eat up the error. */
+
+ q = verify_file(fn, line, !(flags & WRITE_STRING_FILE_AVOID_NEWLINE));
+ if (q <= 0)
+ return r;
+
+ return 0;
+}
+
+int write_string_filef(
+ const char *fn,
+ WriteStringFileFlags flags,
+ const char *format, ...) {
+
+ _cleanup_free_ char *p = NULL;
+ va_list ap;
+ int r;
+
+ va_start(ap, format);
+ r = vasprintf(&p, format, ap);
+ va_end(ap);
+
+ if (r < 0)
+ return -ENOMEM;
+
+ return write_string_file(fn, p, flags);
+}
+
+int read_one_line_file(const char *fn, char **line) {
+ _cleanup_fclose_ FILE *f = NULL;
+ int r;
+
+ assert(fn);
+ assert(line);
+
+ f = fopen(fn, "re");
+ if (!f)
+ return -errno;
+
+ (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
+
+ r = read_line(f, LONG_LINE_MAX, line);
+ return r < 0 ? r : 0;
+}
+
+int verify_file(const char *fn, const char *blob, bool accept_extra_nl) {
+ _cleanup_fclose_ FILE *f = NULL;
+ _cleanup_free_ char *buf = NULL;
+ size_t l, k;
+
+ assert(fn);
+ assert(blob);
+
+ l = strlen(blob);
+
+ if (accept_extra_nl && endswith(blob, "\n"))
+ accept_extra_nl = false;
+
+ buf = malloc(l + accept_extra_nl + 1);
+ if (!buf)
+ return -ENOMEM;
+
+ f = fopen(fn, "re");
+ if (!f)
+ return -errno;
+
+ (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
+
+ /* We try to read one byte more than we need, so that we know whether we hit eof */
+ errno = 0;
+ k = fread(buf, 1, l + accept_extra_nl + 1, f);
+ if (ferror(f))
+ return errno > 0 ? -errno : -EIO;
+
+ if (k != l && k != l + accept_extra_nl)
+ return 0;
+ if (memcmp(buf, blob, l) != 0)
+ return 0;
+ if (k > l && buf[l] != '\n')
+ return 0;
+
+ return 1;
+}
+
+int read_full_stream(
+ FILE *f,
+ char **ret_contents,
+ size_t *ret_size) {
+
+ _cleanup_free_ char *buf = NULL;
+ struct stat st;
+ size_t n, l;
+ int fd;
+
+ assert(f);
+ assert(ret_contents);
+
+ n = LINE_MAX; /* Start size */
+
+ fd = fileno(f);
+ if (fd >= 0) { /* If the FILE* object is backed by an fd (as opposed to memory or such, see fmemopen(), let's
+ * optimize our buffering) */
+
+ if (fstat(fileno(f), &st) < 0)
+ return -errno;
+
+ if (S_ISREG(st.st_mode)) {
+
+ /* Safety check */
+ if (st.st_size > READ_FULL_BYTES_MAX)
+ return -E2BIG;
+
+ /* Start with the right file size, but be prepared for files from /proc which generally report a file
+ * size of 0. Note that we increase the size to read here by one, so that the first read attempt
+ * already makes us notice the EOF. */
+ if (st.st_size > 0)
+ n = st.st_size + 1;
+ }
+ }
+
+ l = 0;
+ for (;;) {
+ char *t;
+ size_t k;
+
+ t = realloc(buf, n + 1);
+ if (!t)
+ return -ENOMEM;
+
+ buf = t;
+ errno = 0;
+ k = fread(buf + l, 1, n - l, f);
+ if (k > 0)
+ l += k;
+
+ if (ferror(f))
+ return errno > 0 ? -errno : -EIO;
+
+ if (feof(f))
+ break;
+
+ /* We aren't expecting fread() to return a short read outside
+ * of (error && eof), assert buffer is full and enlarge buffer.
+ */
+ assert(l == n);
+
+ /* Safety check */
+ if (n >= READ_FULL_BYTES_MAX)
+ return -E2BIG;
+
+ n = MIN(n * 2, READ_FULL_BYTES_MAX);
+ }
+
+ if (!ret_size) {
+ /* Safety check: if the caller doesn't want to know the size of what we just read it will rely on the
+ * trailing NUL byte. But if there's an embedded NUL byte, then we should refuse operation as otherwise
+ * there'd be ambiguity about what we just read. */
+
+ if (memchr(buf, 0, l))
+ return -EBADMSG;
+ }
+
+ buf[l] = 0;
+ *ret_contents = TAKE_PTR(buf);
+
+ if (ret_size)
+ *ret_size = l;
+
+ return 0;
+}
+
+int read_full_file(const char *fn, char **contents, size_t *size) {
+ _cleanup_fclose_ FILE *f = NULL;
+
+ assert(fn);
+ assert(contents);
+
+ f = fopen(fn, "re");
+ if (!f)
+ return -errno;
+
+ (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
+
+ return read_full_stream(f, contents, size);
+}
+
+int executable_is_script(const char *path, char **interpreter) {
+ _cleanup_free_ char *line = NULL;
+ size_t len;
+ char *ans;
+ int r;
+
+ assert(path);
+
+ r = read_one_line_file(path, &line);
+ if (r == -ENOBUFS) /* First line overly long? if so, then it's not a script */
+ return 0;
+ if (r < 0)
+ return r;
+
+ if (!startswith(line, "#!"))
+ return 0;
+
+ ans = strstrip(line + 2);
+ len = strcspn(ans, " \t");
+
+ if (len == 0)
+ return 0;
+
+ ans = strndup(ans, len);
+ if (!ans)
+ return -ENOMEM;
+
+ *interpreter = ans;
+ return 1;
+}
+
+/**
+ * Retrieve one field from a file like /proc/self/status. pattern
+ * should not include whitespace or the delimiter (':'). pattern matches only
+ * the beginning of a line. Whitespace before ':' is skipped. Whitespace and
+ * zeros after the ':' will be skipped. field must be freed afterwards.
+ * terminator specifies the terminating characters of the field value (not
+ * included in the value).
+ */
+int get_proc_field(const char *filename, const char *pattern, const char *terminator, char **field) {
+ _cleanup_free_ char *status = NULL;
+ char *t, *f;
+ size_t len;
+ int r;
+
+ assert(terminator);
+ assert(filename);
+ assert(pattern);
+ assert(field);
+
+ r = read_full_file(filename, &status, NULL);
+ if (r < 0)
+ return r;
+
+ t = status;
+
+ do {
+ bool pattern_ok;
+
+ do {
+ t = strstr(t, pattern);
+ if (!t)
+ return -ENOENT;
+
+ /* Check that pattern occurs in beginning of line. */
+ pattern_ok = (t == status || t[-1] == '\n');
+
+ t += strlen(pattern);
+
+ } while (!pattern_ok);
+
+ t += strspn(t, " \t");
+ if (!*t)
+ return -ENOENT;
+
+ } while (*t != ':');
+
+ t++;
+
+ if (*t) {
+ t += strspn(t, " \t");
+
+ /* Also skip zeros, because when this is used for
+ * capabilities, we don't want the zeros. This way the
+ * same capability set always maps to the same string,
+ * irrespective of the total capability set size. For
+ * other numbers it shouldn't matter. */
+ t += strspn(t, "0");
+ /* Back off one char if there's nothing but whitespace
+ and zeros */
+ if (!*t || isspace(*t))
+ t--;
+ }
+
+ len = strcspn(t, terminator);
+
+ f = strndup(t, len);
+ if (!f)
+ return -ENOMEM;
+
+ *field = f;
+ return 0;
+}
+
+DIR *xopendirat(int fd, const char *name, int flags) {
+ int nfd;
+ DIR *d;
+
+ assert(!(flags & O_CREAT));
+
+ nfd = openat(fd, name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|flags, 0);
+ if (nfd < 0)
+ return NULL;
+
+ d = fdopendir(nfd);
+ if (!d) {
+ safe_close(nfd);
+ return NULL;
+ }
+
+ return d;
+}
+
+static int search_and_fopen_internal(const char *path, const char *mode, const char *root, char **search, FILE **_f) {
+ char **i;
+
+ assert(path);
+ assert(mode);
+ assert(_f);
+
+ if (!path_strv_resolve_uniq(search, root))
+ return -ENOMEM;
+
+ STRV_FOREACH(i, search) {
+ _cleanup_free_ char *p = NULL;
+ FILE *f;
+
+ if (root)
+ p = strjoin(root, *i, "/", path);
+ else
+ p = strjoin(*i, "/", path);
+ if (!p)
+ return -ENOMEM;
+
+ f = fopen(p, mode);
+ if (f) {
+ *_f = f;
+ return 0;
+ }
+
+ if (errno != ENOENT)
+ return -errno;
+ }
+
+ return -ENOENT;
+}
+
+int search_and_fopen(const char *path, const char *mode, const char *root, const char **search, FILE **_f) {
+ _cleanup_strv_free_ char **copy = NULL;
+
+ assert(path);
+ assert(mode);
+ assert(_f);
+
+ if (path_is_absolute(path)) {
+ FILE *f;
+
+ f = fopen(path, mode);
+ if (f) {
+ *_f = f;
+ return 0;
+ }
+
+ return -errno;
+ }
+
+ copy = strv_copy((char**) search);
+ if (!copy)
+ return -ENOMEM;
+
+ return search_and_fopen_internal(path, mode, root, copy, _f);
+}
+
+int search_and_fopen_nulstr(const char *path, const char *mode, const char *root, const char *search, FILE **_f) {
+ _cleanup_strv_free_ char **s = NULL;
+
+ if (path_is_absolute(path)) {
+ FILE *f;
+
+ f = fopen(path, mode);
+ if (f) {
+ *_f = f;
+ return 0;
+ }
+
+ return -errno;
+ }
+
+ s = strv_split_nulstr(search);
+ if (!s)
+ return -ENOMEM;
+
+ return search_and_fopen_internal(path, mode, root, s, _f);
+}
+
+int fflush_and_check(FILE *f) {
+ assert(f);
+
+ errno = 0;
+ fflush(f);
+
+ if (ferror(f))
+ return errno > 0 ? -errno : -EIO;
+
+ return 0;
+}
+
+int fflush_sync_and_check(FILE *f) {
+ int r;
+
+ assert(f);
+
+ r = fflush_and_check(f);
+ if (r < 0)
+ return r;
+
+ if (fsync(fileno(f)) < 0)
+ return -errno;
+
+ r = fsync_directory_of_file(fileno(f));
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+int write_timestamp_file_atomic(const char *fn, usec_t n) {
+ char ln[DECIMAL_STR_MAX(n)+2];
+
+ /* Creates a "timestamp" file, that contains nothing but a
+ * usec_t timestamp, formatted in ASCII. */
+
+ if (n <= 0 || n >= USEC_INFINITY)
+ return -ERANGE;
+
+ xsprintf(ln, USEC_FMT "\n", n);
+
+ return write_string_file(fn, ln, WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_ATOMIC);
+}
+
+int read_timestamp_file(const char *fn, usec_t *ret) {
+ _cleanup_free_ char *ln = NULL;
+ uint64_t t;
+ int r;
+
+ r = read_one_line_file(fn, &ln);
+ if (r < 0)
+ return r;
+
+ r = safe_atou64(ln, &t);
+ if (r < 0)
+ return r;
+
+ if (t <= 0 || t >= (uint64_t) USEC_INFINITY)
+ return -ERANGE;
+
+ *ret = (usec_t) t;
+ return 0;
+}
+
+int fputs_with_space(FILE *f, const char *s, const char *separator, bool *space) {
+ int r;
+
+ assert(s);
+
+ /* Outputs the specified string with fputs(), but optionally prefixes it with a separator. The *space parameter
+ * when specified shall initially point to a boolean variable initialized to false. It is set to true after the
+ * first invocation. This call is supposed to be use in loops, where a separator shall be inserted between each
+ * element, but not before the first one. */
+
+ if (!f)
+ f = stdout;
+
+ if (space) {
+ if (!separator)
+ separator = " ";
+
+ if (*space) {
+ r = fputs(separator, f);
+ if (r < 0)
+ return r;
+ }
+
+ *space = true;
+ }
+
+ return fputs(s, f);
+}
+
+/* A bitmask of the EOL markers we know */
+typedef enum EndOfLineMarker {
+ EOL_NONE = 0,
+ EOL_ZERO = 1 << 0, /* \0 (aka NUL) */
+ EOL_TEN = 1 << 1, /* \n (aka NL, aka LF) */
+ EOL_THIRTEEN = 1 << 2, /* \r (aka CR) */
+} EndOfLineMarker;
+
+static EndOfLineMarker categorize_eol(char c, ReadLineFlags flags) {
+
+ if (!IN_SET(flags, READ_LINE_ONLY_NUL)) {
+ if (c == '\n')
+ return EOL_TEN;
+ if (c == '\r')
+ return EOL_THIRTEEN;
+ }
+
+ if (c == '\0')
+ return EOL_ZERO;
+
+ return EOL_NONE;
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(FILE*, funlockfile);
+
+int read_line_full(FILE *f, size_t limit, ReadLineFlags flags, char **ret) {
+ size_t n = 0, allocated = 0, count = 0;
+ _cleanup_free_ char *buffer = NULL;
+ int r;
+
+ assert(f);
+
+ /* Something like a bounded version of getline().
+ *
+ * Considers EOF, \n, \r and \0 end of line delimiters (or combinations of these), and does not include these
+ * delimiters in the string returned. Specifically, recognizes the following combinations of markers as line
+ * endings:
+ *
+ * • \n (UNIX)
+ * • \r (old MacOS)
+ * • \0 (C strings)
+ * • \n\0
+ * • \r\0
+ * • \r\n (Windows)
+ * • \n\r
+ * • \r\n\0
+ * • \n\r\0
+ *
+ * Returns the number of bytes read from the files (i.e. including delimiters — this hence usually differs from
+ * the number of characters in the returned string). When EOF is hit, 0 is returned.
+ *
+ * The input parameter limit is the maximum numbers of characters in the returned string, i.e. excluding
+ * delimiters. If the limit is hit we fail and return -ENOBUFS.
+ *
+ * If a line shall be skipped ret may be initialized as NULL. */
+
+ if (ret) {
+ if (!GREEDY_REALLOC(buffer, allocated, 1))
+ return -ENOMEM;
+ }
+
+ {
+ _unused_ _cleanup_(funlockfilep) FILE *flocked = f;
+ EndOfLineMarker previous_eol = EOL_NONE;
+ flockfile(f);
+
+ for (;;) {
+ EndOfLineMarker eol;
+ char c;
+
+ if (n >= limit)
+ return -ENOBUFS;
+
+ if (count >= INT_MAX) /* We couldn't return the counter anymore as "int", hence refuse this */
+ return -ENOBUFS;
+
+ r = safe_fgetc(f, &c);
+ if (r < 0)
+ return r;
+ if (r == 0) /* EOF is definitely EOL */
+ break;
+
+ eol = categorize_eol(c, flags);
+
+ if (FLAGS_SET(previous_eol, EOL_ZERO) ||
+ (eol == EOL_NONE && previous_eol != EOL_NONE) ||
+ (eol != EOL_NONE && (previous_eol & eol) != 0)) {
+ /* Previous char was a NUL? This is not an EOL, but the previous char was? This type of
+ * EOL marker has been seen right before? In either of these three cases we are
+ * done. But first, let's put this character back in the queue. (Note that we have to
+ * cast this to (unsigned char) here as ungetc() expects a positive 'int', and if we
+ * are on an architecture where 'char' equals 'signed char' we need to ensure we don't
+ * pass a negative value here. That said, to complicate things further ungetc() is
+ * actually happy with most negative characters and implicitly casts them back to
+ * positive ones as needed, except for \xff (aka -1, aka EOF), which it refuses. What a
+ * godawful API!) */
+ assert_se(ungetc((unsigned char) c, f) != EOF);
+ break;
+ }
+
+ count++;
+
+ if (eol != EOL_NONE) {
+ previous_eol |= eol;
+ continue;
+ }
+
+ if (ret) {
+ if (!GREEDY_REALLOC(buffer, allocated, n + 2))
+ return -ENOMEM;
+
+ buffer[n] = c;
+ }
+
+ n++;
+ }
+ }
+
+ if (ret) {
+ buffer[n] = 0;
+
+ *ret = TAKE_PTR(buffer);
+ }
+
+ return (int) count;
+}
+
+int safe_fgetc(FILE *f, char *ret) {
+ int k;
+
+ assert(f);
+
+ /* A safer version of plain fgetc(): let's propagate the error that happened while reading as such, and
+ * separate the EOF condition from the byte read, to avoid those confusion signed/unsigned issues fgetc()
+ * has. */
+
+ errno = 0;
+ k = fgetc(f);
+ if (k == EOF) {
+ if (ferror(f))
+ return errno > 0 ? -errno : -EIO;
+
+ if (ret)
+ *ret = 0;
+
+ return 0;
+ }
+
+ if (ret)
+ *ret = k;
+
+ return 1;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-08-13 10:11:03 +0000