| 1 | #define _GNU_SOURCE |
| 2 | #undef sun |
| 3 | |
| 4 | #include <errno.h> |
| 5 | #include <stdarg.h> |
| 6 | #include <stdio.h> |
| 7 | #include <string.h> |
| 8 | |
| 9 | #include <unistd.h> |
| 10 | #include <dlfcn.h> |
| 11 | #include <fcntl.h> |
| 12 | |
| 13 | #include <sys/socket.h> |
| 14 | #include <sys/stat.h> |
| 15 | #include <sys/un.h> |
| 16 | |
| 17 | #define IMPORTS(_) \ |
| 18 | _(open, int, (const char *, int, ...)) \ |
| 19 | _(open64, int, (const char *, int, ...)) \ |
| 20 | _(fopen, FILE *, (const char *, const char *)) \ |
| 21 | _(freopen, FILE *, (const char *, const char *, FILE *)) |
| 22 | |
| 23 | #define DECL(imp, ret, args) static ret (*real_##imp) args; |
| 24 | IMPORTS(DECL) |
| 25 | #undef DECL |
| 26 | |
| 27 | static void setup(void) __attribute__((constructor)); |
| 28 | static void import(void) |
| 29 | { |
| 30 | #define IMPORT(imp, ret, args) \ |
| 31 | real_##imp = (ret (*)args)dlsym(RTLD_NEXT, #imp); |
| 32 | IMPORTS(IMPORT) |
| 33 | #undef IMPORT |
| 34 | } |
| 35 | |
| 36 | #define SA(sa) ((struct sockaddr *)(sa)) |
| 37 | |
| 38 | #define PRESERVING_ERRNO(body) do { \ |
| 39 | int _err = errno; { body } errno = _err; \ |
| 40 | } while (0) |
| 41 | |
| 42 | static int maybe_connect(const char *fn, int *fdp) |
| 43 | { |
| 44 | int fd; |
| 45 | struct sockaddr_un sun; |
| 46 | struct stat st; |
| 47 | |
| 48 | if (stat(fn, &st) || !S_ISSOCK(st.st_mode)) |
| 49 | return (0); |
| 50 | *fdp = -1; |
| 51 | if (strlen(fn) >= sizeof(sun.sun_path)) { |
| 52 | errno = EINVAL; |
| 53 | return (1); |
| 54 | } |
| 55 | strncpy(sun.sun_path, fn, sizeof(sun.sun_path)); |
| 56 | sun.sun_family = AF_UNIX; |
| 57 | if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0 || |
| 58 | connect(fd, SA(&sun), SUN_LEN(&sun))) { |
| 59 | PRESERVING_ERRNO( if (fd >= 0) close(fd); ); |
| 60 | return (1); |
| 61 | } |
| 62 | *fdp = fd; |
| 63 | return (1); |
| 64 | } |
| 65 | |
| 66 | #define OPEN_VENEER(open) \ |
| 67 | int open(const char *fn, int how, ...) \ |
| 68 | { \ |
| 69 | int mode = 0; \ |
| 70 | int fd; \ |
| 71 | va_list ap; \ |
| 72 | \ |
| 73 | PRESERVING_ERRNO({ \ |
| 74 | if (how & O_CREAT) \ |
| 75 | { va_start(ap, how); mode = va_arg(ap, int); va_end(ap); } \ |
| 76 | if (!maybe_connect(fn, &fd)) fd = real_##open(fn, how, mode); \ |
| 77 | if (fd < 0) return (-1); \ |
| 78 | }); \ |
| 79 | return (fd); \ |
| 80 | } |
| 81 | OPEN_VENEER(open) |
| 82 | OPEN_VENEER(open64) |
| 83 | |
| 84 | FILE *fopen(const char *fn, const char *how) |
| 85 | { |
| 86 | int fd; |
| 87 | FILE *fp = 0; |
| 88 | |
| 89 | PRESERVING_ERRNO({ |
| 90 | if (!maybe_connect(fn, &fd)) |
| 91 | fp = real_fopen(fn, how); |
| 92 | else if (fd >= 0 && (fp = fdopen(fd, how)) == 0) |
| 93 | PRESERVING_ERRNO( close(fd); ); |
| 94 | }); |
| 95 | return (fp); |
| 96 | } |
| 97 | |
| 98 | FILE *freopen(const char *fn, const char *how, FILE *fp) |
| 99 | { |
| 100 | int fd; |
| 101 | |
| 102 | PRESERVING_ERRNO({ |
| 103 | if (!maybe_connect(fn, &fd)) |
| 104 | fp = real_freopen(fn, how, fp); |
| 105 | else if (fd >= 0) { |
| 106 | if (fflush(fp) || dup2(fd, fileno(fp))) fp = 0; |
| 107 | PRESERVING_ERRNO( close(fd); ); |
| 108 | } |
| 109 | }); |
| 110 | return (fp); |
| 111 | } |
| 112 | |
| 113 | static void setup(void) |
| 114 | { |
| 115 | PRESERVING_ERRNO({ |
| 116 | import(); |
| 117 | }); |
| 118 | } |