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authorMattias Andrée <maandree@kth.se>2023-11-17 18:25:16 +0100
committerMattias Andrée <maandree@kth.se>2023-11-17 18:25:16 +0100
commit53b1ee331f7bf40a1db1edfed863695a104b4e1e (patch)
treeca484ee59c1733dbbdafd86cfee50192421fb15b /sshexec.c
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First commit
Signed-off-by: Mattias Andrée <maandree@kth.se>
Diffstat (limited to 'sshexec.c')
-rw-r--r--sshexec.c224
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));
+}