diff options
Diffstat (limited to 'sshexec.c')
| -rw-r--r-- | sshexec.c | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/sshexec.c b/sshexec.c new file mode 100644 index 0000000..b5eae7c --- /dev/null +++ b/sshexec.c @@ -0,0 +1,224 @@ +/* See LICENSE file for copyright and license details. */ +#include <ctype.h> +#include <errno.h> +#include <limits.h> +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + + +static const char *argv0 = "sshexec"; + + +#define exitf(...) (fprintf(stderr, __VA_ARGS__), exit(255)) + + +static void +usage(void) +{ + exitf("usage: %s { %s } [ssh-option] ... destination command [argument] ...\n", + argv0, "[ssh=command] [dir=directory]"); +} + +static const enum optclass { + NO_RECOGNISED = 0, + NO_ARGUMENT, + MANDATORY_ARGUMENT +} sshopts[(size_t)1 << CHAR_BIT] = { +#define X(F) [F] = NO_ARGUMENT + X('4'), X('6'), X('A'), X('a'), X('C'), X('f'), X('G'), + X('g'), X('K'), X('k'), X('M'), X('N'), X('n'), X('q'), + X('s'), X('T'), X('t'), X('V'), X('v'), X('X'), X('x'), + X('Y'), X('y'), +#undef X +#define X(F) [F] = MANDATORY_ARGUMENT + X('B'), X('b'), X('c'), X('D'), X('E'), X('e'), X('F'), + X('I'), X('i'), X('J'), X('L'), X('l'), X('m'), X('O'), + X('o'), X('P'), X('p'), X('Q'), X('R'), X('S'), X('W'), + X('w') +#undef X +}; + +static char *command = NULL; +static size_t command_size = 0; +static size_t command_len = 0; + + +#define build_command(DATA, N)\ + do {\ + build_command_reserve(N);\ + memcpy(&command[command_len], (DATA), (N));\ + command_len += (N);\ + } while (0) + +#define build_command_asis(S)\ + build_command(S, sizeof(S) - 1) + +#define finalise_command()\ + build_command("", 1) + + +static void +build_command_reserve(size_t n) +{ + if (n > command_size - command_len) { + if (n < 512) + n = 512; + if (command_len + n > SIZE_MAX) + exitf("%s: could not allocate enough memory\n", argv0); + command_size = command_len + n; + command = realloc(command, command_size); + if (!command) + exitf("%s: could not allocate enough memory\n", argv0); + } +} + + +static void +build_command_escape(const char *arg) +{ + size_t n = 0; + if (!*arg) { + build_command_asis("''"); + return; + } + while (isalnum(arg[n]) || arg[n] == '_' || arg[n] == '/') + n += 1; + if (!arg[n]) { + build_command(arg, n); + return; + } + build_command_asis("\"$(printf '"); + goto start; + while (*arg) { + build_command_reserve(4); + command[command_len++] = '\\'; + command[command_len] = (((unsigned char)*arg >> 6) & 7) + '0'; + command_len += (command[command_len] != '0'); + command[command_len] = (((unsigned char)*arg >> 3) & 7) + '0'; + command_len += (command[command_len] != '0'); + command[command_len++] = ((unsigned char)*arg & 7) + '0'; + arg = &arg[1]; + + n = 0; + while (isalpha(arg[n]) || arg[n] == '_' || arg[n] == '/') + n += 1; + if (n) { + while (isalnum(arg[n]) || arg[n] == '_' || arg[n] == '/') + n += 1; + start: + build_command(arg, n); + arg = &arg[n]; + } + } + build_command_asis("\\n')\""); +} + + +int +main(int argc_unused, char *argv[]) +{ + const char *dir = NULL; + const char *ssh = NULL; + const char *destination; + char **opts; + size_t nopts; + enum optclass class; + const char *arg; + char opt; + const char **args; + size_t i; + + (void) argc_unused; + + if (*argv) + argv0 = *argv++; + +#define STORE_OPT(VARP, OPT)\ + if (!strncmp(*argv, OPT"=", sizeof(OPT))) {\ + if (*(VARP) || !*(*(VARP) = &(*argv)[sizeof(OPT)]))\ + usage();\ + continue;\ + } + if (*argv && !strcmp(*argv, "{")) { + argv++; + for (; *argv && strcmp(*argv, "}"); argv++) { + STORE_OPT(&ssh, "ssh") + STORE_OPT(&dir, "dir") + usage(); + } + if (!*argv) + usage(); + argv++; + } +#undef STORE_OPT + + if (!ssh) + ssh = "ssh"; + + opts = argv; + nopts = 0; + while (*argv) { + if (!strcmp(*argv, "--")) { + argv++; + break; + } else if ((*argv)[0] != '-' || !(*argv)[1]) { + break; + } + arg = &(*argv++)[1]; + nopts++; + while (*arg) { + opt = *arg++; + class = sshopts[(unsigned char)opt]; + if (class == MANDATORY_ARGUMENT) { + if (*arg) { + break; + } else if (*argv) { + argv++; + nopts++; + break; + } else { + exitf("%s: argument missing for option -%c\n", argv0, opt); + } + } else if (class == NO_RECOGNISED) { + exitf("%s: unrecognised option -%c\n", argv0, opt); + } + } + } + + destination = *argv++; + if (!destination && !*argv) + usage(); + + if (dir) { + build_command_asis("cd -- "); + build_command_escape(dir); + build_command_asis(" && "); + } + build_command_asis("exec --"); + for (; *argv; argv++) { + build_command_asis(" "); + build_command_escape(*argv); + } + finalise_command(); + + i = 0; + args = calloc(5 + nopts, sizeof(*args)); + if (!args) + exitf("%s: could not allocate enough memory\n", argv0); + args[i++] = ssh; + memcpy(&args[i], opts, nopts * sizeof(*opts)); + i += nopts; + args[i++] = "--"; + args[i++] = destination; + args[i++] = command; + args[i++] = NULL; + +#if defined(__GNUC__) +# pragma GCC diagnostic ignored "-Wcast-qual" +#endif + execvp(ssh, (char **)args); + exitf("%s: failed to execute %s: %s\n", argv0, ssh, strerror(errno)); +} |