1 // Copyright (2013) Jann Horn <jann@thejh.net>
2 // This code is licensed under the AGPLv3.
4 HEADER #include <sys/types.h>
15 // Wrapper for `read` that retries on partial reads.
16 // If last_res is non-NULL, it will be filled with the
17 // result of the last read() call (but all positive numbers
18 // become 1). In other words:
21 // - 1: no problems occured
22 PUBLIC_FN ssize_t read_nointr(int fd, void *buf, size_t count, int *last_res) {
25 while (done < count) {
26 ssize_t part_res = read(fd, buf+done, count-done);
28 if (last_res) *last_res = part_res;
29 if (done) return done;
34 if (last_res) *last_res = 1;
38 // Wrapper for `write` that retries on partial writes.
39 // If last_res is non-NULL, it will be filled with the
40 // result of the last write() call (but all positive numbers
41 // become 1). In other words:
44 // - 1: no problems occured
45 PUBLIC_FN ssize_t write_nointr(int fd, void *buf, size_t count, int *last_res) {
48 while (done < count) {
49 ssize_t part_res = write(fd, buf+done, count-done);
51 if (last_res) *last_res = part_res;
52 if (done) return done;
57 if (last_res) *last_res = 1;
61 // Read all data from the given file descriptor. Tries fstat()+read()
62 // first, but if fstat() doesn't work, falls back to multiple read()s.
63 // Specify JH_NO_STAT to prevent the fstat() call.
64 // The return value is a malloc'd buffer.
65 // The buffer will be null-terminated, so you can read text files with
66 // this and can specify len_out as NULL.
67 PUBLIC_CONST JH_SLURP_NO_STAT 1
68 PUBLIC_CONST JH_SLURP_REALLOC 2 /* realloc result block if it saves RAM */
69 PUBLIC_CONST JH_SLURP_8BYTE_PAD 4 /* pad buffer with eight nullbytes, not one */
70 PUBLIC_CONST JH_SLURP_FIXSIZE 8 /* len_out is actually input and specifies
71 HEADER the expected length. if there is more data,
72 HEADER that might be ignored silently. */
73 PUBLIC_FN void *slurp_fd(int fd, size_t *len_out, int flags) {
76 // Let's just guess that the file is 1023 bytes. Will become 1024 with
78 size_t size_guess = 1023;
79 bool trusted_guess = false; /* can we rely on the guess? */
81 if (flags&JH_SLURP_FIXSIZE) {
82 size_guess = *len_out;
84 // if we want a fixed size, of course we don't want to stat
85 flags |= JH_SLURP_NO_STAT;
88 int padlen = (flags&JH_SLURP_8BYTE_PAD)?8:1;
90 // If we can determine the exact size, we don't have to guess. So try
91 // to determine the exact size.
92 if (!(flags&JH_SLURP_NO_STAT)) {
94 if (fstat(fd, &st) == 0) {
96 size_guess = st.st_size;
106 buf = realloc(buf, size_guess+padlen);
107 if (buf == NULL) return NULL;
109 ssize_t read_res = read_nointr(fd, buf+done, size_guess-done, &last_res);
110 if (last_res == -1) { errno_=errno; free(buf); errno=errno_; return NULL; }
112 if (last_res == 0 || trusted_guess) {
117 *(uint64_t*)(buf+done) = 0;
119 if (done != size_guess && (flags&JH_SLURP_REALLOC)) {
120 // Well, it'd be weird if shrinking could fail... but meh, I can't find
121 // an explicit statement about this being disallowed, so try staying on
123 char *buf_ = realloc(buf, done+padlen);
124 if (buf_) buf = buf_;
126 if (done != size_guess && (flags&JH_SLURP_FIXSIZE)) {
128 // not the most correct error message ever, but whatever.
132 if (len_out) *len_out = done;
135 size_guess<<=1; // try two times the buffer size
139 PUBLIC_FN void *slurp_file(char *path, size_t *len_out, int flags) {
140 int fd = open(path, O_RDONLY|O_CLOEXEC);
141 if (fd == -1) return NULL;
142 char *res = slurp_fd(fd, len_out, flags);
149 // Write data into a file. len can be -1; that means that
150 // the real length is strlen(buf).
151 PUBLIC_FN int write_file(char *path, void *buf, ssize_t len, int open_flags) {
152 if (len == -1) len = strlen(buf);
154 int fd = open(path, open_flags|O_CLOEXEC|O_WRONLY, 0777);
155 if (fd == -1) return 1;
156 ssize_t write_res = write_nointr(fd, buf, len, NULL);
157 int write_errno = errno;
158 int close_res = close(fd);
159 if (write_res != len) {
163 if (close_res) return 1;
167 PUBLIC_FN void *mmap_file(void *addr, size_t length, int prot, int flags, char *path, off_t offset) {
168 assert((flags&MAP_ANONYMOUS) == 0);
169 assert(prot&(PROT_EXEC|PROT_READ|PROT_WRITE));
170 int open_flags = O_CLOEXEC;
171 if ((prot & (PROT_READ|PROT_EXEC)) && !(prot&PROT_WRITE)) open_flags |= O_RDONLY;
172 else if ((prot & (PROT_READ|PROT_EXEC))) open_flags |= O_RDWR;
173 else open_flags |= O_WRONLY;
174 int fd = open(path, open_flags);
175 if (fd == -1) return NULL;
176 void *r = mmap(addr, length, prot, flags, fd, offset);
180 return (r==MAP_FAILED) ? NULL : r;