* Emit a binary patch. Implements (an approximation of) the pipeline: * cat bin1 | xxd > tmp.1 * cat bin2 | xxd > tmp.2 * diff tmp.1 tmp.2 | gzip > filename * rm tmp.1 tmp.2 */
| 66 | * rm tmp.1 tmp.2 |
| 67 | */ |
| 68 | void emitPatch(const char *filename, const char *compress, int fd1, |
| 69 | const uint8_t *bin2, size_t len2) |
| 70 | { |
| 71 | char fifo_name1[64], fifo_name2[64], *fifo_name = nullptr; |
| 72 | int fd, fds2[2], fds3[2]; |
| 73 | static unsigned CHILD_MAX = 4; |
| 74 | pid_t pids[CHILD_MAX]; |
| 75 | const char *progs[CHILD_MAX]; |
| 76 | unsigned pc = 0; |
| 77 | uint64_t rand64[2]; |
| 78 | |
| 79 | // Create named pipes: |
| 80 | fd = open("/dev/urandom", O_RDONLY); |
| 81 | if (fd < 0) |
| 82 | error("failed to open \"/dev/urandom\": %s", strerror(errno)); |
| 83 | if (read(fd, (void *)rand64, sizeof(rand64)) != sizeof(rand64)) |
| 84 | error("failed to read from \"/dev/urandom\": %s", strerror(errno)); |
| 85 | close(fd); |
| 86 | pid_t pid = getpid(); |
| 87 | int r = snprintf(fifo_name1, sizeof(fifo_name1)-1, |
| 88 | "/tmp/bin1_%d_%.16lX.hex", pid, rand64[0]); |
| 89 | if (r < 0 || r >= (int)sizeof(fifo_name1)) |
| 90 | { |
| 91 | name_error: |
| 92 | error("failed to generate named pipe name: %s", strerror(errno)); |
| 93 | } |
| 94 | r = snprintf(fifo_name2, sizeof(fifo_name2)-1, "/tmp/bin2_%d_%.16lX.hex", |
| 95 | pid, rand64[1]); |
| 96 | if (r < 0 || r >= (int)sizeof(fifo_name1)) |
| 97 | goto name_error; |
| 98 | if (mkfifo(fifo_name1, S_IRUSR | S_IWUSR) != 0 || |
| 99 | mkfifo(fifo_name2, S_IRUSR | S_IWUSR) != 0) |
| 100 | error("failed to create named pipe: %s", strerror(errno)); |
| 101 | |
| 102 | // Execute xxd #1 |
| 103 | progs[pc] = "xxd"; |
| 104 | pids[pc] = fork(); |
| 105 | if (pids[pc] == 0) |
| 106 | { |
| 107 | if (dup2(fd1, STDIN_FILENO) < 0) |
| 108 | { |
| 109 | dup2_error: |
| 110 | error("failed to dup file descriptor: %s", strerror(errno)); |
| 111 | } |
| 112 | close(fd1); |
| 113 | fifo_name = fifo_name1; |
| 114 | fd = open(fifo_name, O_WRONLY); |
| 115 | if (fd < 0) |
| 116 | { |
| 117 | open_error: |
| 118 | error("failed to open named pipe: %s", strerror(errno)); |
| 119 | } |
| 120 | if (dup2(fd, STDOUT_FILENO) < 0) |
| 121 | goto dup2_error; |
| 122 | close(fd); |
| 123 | if (execlp(progs[pc], progs[pc], "-p", nullptr) != 0) |
| 124 | { |
| 125 | execlp_error: |
no test coverage detected