stupidtools/tests/unit/test_sh_emit.c

/* LINK: ../../src/gen/sh_emit.c ../../src/error.c ../../src/span.c */
#define _POSIX_C_SOURCE 200809L /* mkdtemp(3) under -std=c23 */
/* tests/unit/test_sh_emit.c
 *
 * Unit tests for the POSIX-sh text emitter (todo 15).
 *
 * The magic LINK comment on line 1 is REQUIRED by tests/run.sh: it lists
 * the extra .c sources to compile into this test binary (paths relative
 * to tests/unit/, space-separated). munit.c and the include dirs are
 * added automatically by the harness.
 *
 * Strategy: st_sh_quote() is the load-bearing primitive, so the core
 * proof is the ROUND-TRIP — the quoted literal, dropped into a real
 * shell script as `v=<quoted>; printf '%s' "$v" > <out>`, must reproduce
 * the exact input bytes when the script is executed by sh, bash and zsh.
 * The same machinery proves the injection attempt stays inert.
 *
 * No command substitution is used to capture output anywhere here: it
 * strips trailing newlines, which would mask a broken round-trip.
 */
#include "munit.h"

#include "error.h"
#include "gen/sh_emit.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>

/* Per-test temp dir, created in setup, removed in teardown. */
static char temp_dir[128];

static void *
setup(const MunitParameter params[], void *user_data)
{
    (void)params;
    (void)user_data;
    if (snprintf(temp_dir, sizeof temp_dir, "/tmp/st_emit_XXXXXX") < 0) {
        return NULL;
    }
    if (mkdtemp(temp_dir) == NULL) {
        return NULL;
    }
    return (void *)1;
}

static void
teardown(void *fixture)
{
    char cmd[160];

    if (fixture == NULL || temp_dir[0] == '\0') {
        return;
    }
    if (snprintf(cmd, sizeof cmd, "rm -rf -- '%s'", temp_dir) < 0) {
        return;
    }
    (void)system(cmd); /* best-effort; mkdtemp names are [A-Za-z0-9_]* */
    temp_dir[0] = '\0';
}

/* Run "<shell> -n <path>", return the shell's exit status, or -1 if the
 * command could not even be spawned. */
static int
syntax_check(const char *shell, const char *path)
{
    char cmd[512];
    int rc;

    if (snprintf(cmd, sizeof cmd, "%s -n %s", shell, path) < 0) {
        return -1;
    }
    rc = system(cmd);
    if (rc == -1) {
        return -1;
    }
    return WEXITSTATUS(rc);
}

/* Round-trip `value` through one shell: write a script that assigns
 * st_sh_quote(value) to a variable and printf's it into a file, execute
 * it, and byte-compare the file with the original. Returns the shell's
 * exit status, or -1 on setup failure. */
static int
roundtrip_one(const char *shell, const char *value, size_t len,
              const char *pathbase)
{
    char script_path[512];
    char out_path[512];
    char *q, *qout;
    FILE *f;
    FILE *in;
    char *got;
    long n;
    int rc;

    q = st_sh_quote_n(value, len, NULL);
    if (q == NULL) {
        return -1;
    }
    if (snprintf(script_path, sizeof script_path, "%s/%s.sh", temp_dir,
                 pathbase) < 0) {
        free(q);
        return -1;
    }
    if (snprintf(out_path, sizeof out_path, "%s/%s.out", temp_dir,
                 pathbase) < 0) {
        free(q);
        return -1;
    }
    qout = st_sh_quote(out_path);
    if (qout == NULL) {
        free(q);
        return -1;
    }
    f = fopen(script_path, "w");
    if (f == NULL) {
        free(q);
        free(qout);
        return -1;
    }
    /* q and qout are st_sh_quote() output: shell-safe by construction. */
    if (fprintf(f, "v=%s\nprintf '%%s' \"$v\" > %s\n", q, qout) < 0) {
        fclose(f);
        free(q);
        free(qout);
        return -1;
    }
    fclose(f);
    free(q);
    free(qout);

    {
        char cmd[1200];
        int spawned;

        if (snprintf(cmd, sizeof cmd, "%s %s", shell, script_path) < 0) {
            return -1;
        }
        spawned = system(cmd);
        if (spawned == -1) {
            return -1;
        }
        rc = WEXITSTATUS(spawned);
    }
    if (rc != 0) {
        return rc;
    }
    in = fopen(out_path, "rb");
    if (in == NULL) {
        return -1;
    }
    if (fseek(in, 0, SEEK_END) != 0) {
        fclose(in);
        return -1;
    }
    n = ftell(in);
    if (n < 0 || fseek(in, 0, SEEK_SET) != 0) {
        fclose(in);
        return -1;
    }
    got = munit_malloc((size_t)n + 1);
    if (fread(got, 1, (size_t)n, in) != (size_t)n) {
        free(got);
        fclose(in);
        return -1;
    }
    fclose(in);
    got[n] = '\0';
    if ((size_t)n != len || memcmp(got, value, len) != 0) {
        free(got);
        return -2; /* round-trip mismatch */
    }
    free(got);
    return 0;
}

/* Round-trip through sh, bash and zsh; -2 means content mismatch. */
static void
roundtrip_assert(const char *value, size_t len, const char *pathbase)
{
    munit_assert_int(roundtrip_one("sh", value, len, pathbase), ==, 0);
    munit_assert_int(roundtrip_one("bash", value, len, pathbase), ==, 0);
    munit_assert_int(roundtrip_one("zsh", value, len, pathbase), ==, 0);
}

static void
roundtrip_assert_str(const char *value, const char *pathbase)
{
    roundtrip_assert(value, strlen(value), pathbase);
}

/* --- exact literal format ------------------------------------------------- */

static MunitResult
test_quote_empty(const MunitParameter params[], void *data)
{
    (void)params;
    (void)data;
    char *q = st_sh_quote("");

    munit_assert_not_null(q);
    munit_assert_string_equal(q, "''");
    free(q);
    return MUNIT_OK;
}

static MunitResult
test_quote_plain(const MunitParameter params[], void *data)
{
    (void)params;
    (void)data;
    char *q = st_sh_quote("abc");

    munit_assert_not_null(q);
    munit_assert_string_equal(q, "'abc'");
    free(q);
    return MUNIT_OK;
}

/* The canonical escape shape is locked byte-for-byte: each `'` becomes
 * the 4-char sequence '\'' between the two surrounding quotes. */
static MunitResult
test_quote_literal_format(const MunitParameter params[], void *data)
{
    (void)params;
    (void)data;
    char *q;

    q = st_sh_quote("'");
    munit_assert_not_null(q);
    munit_assert_string_equal(q, "''\\'''");
    free(q);

    q = st_sh_quote("a'b");
    munit_assert_not_null(q);
    munit_assert_string_equal(q, "'a'\\''b'");
    free(q);
    return MUNIT_OK;
}

/* --- round-trips through real shells -------------------------------------- */

static MunitResult
test_quote_roundtrip_fixed(const MunitParameter params[], void *data)
{
    (void)params;
    (void)data;
    static const char *const hostile[] = {
        "a'b\"c $d",
        "''",
        "'''",
        "$(rm -rf /)",
        "`rm -rf /`",
        "\\", "$", "\"", "'", "`",
        "line1\nline2\n",
        "\nleading",
        "trailing\n",
        "\t tab\t$HOME\t",
        "$PATH ${HOME} ~ *.txt ?[a] ; | & > <",
        "#! /bin/sh",
        "--prefix=/tmp/x y",
        "=;:,%^(){}[]<>!#~",
        "h\xC3\xA9llo w\xC3\xB6rld \xE2\x9C\x93", /* UTF-8 */
        "",
    };
    size_t i;

    for (i = 0; i < sizeof hostile / sizeof hostile[0]; i++) {
        char base[64];

        if (snprintf(base, sizeof base, "fixed%zu", i) < 0) {
            return MUNIT_ERROR;
        }
        roundtrip_assert_str(hostile[i], base);
    }
    return MUNIT_OK;
}

/* xorshift32 with a fixed seed: deterministic property test. */
static uint32_t rng_state = 0x2E3A5B7Fu;

static uint32_t
rng_next(void)
{
    uint32_t x = rng_state;

    x ^= x << 13;
    x ^= x >> 17;
    x ^= x << 5;
    rng_state = x;
    return x;
}

static MunitResult
test_quote_roundtrip_random(const MunitParameter params[], void *data)
{
    (void)params;
    (void)data;
    /* Hostile alphabet: every byte class that matters to a shell. */
    static const char alphabet[] =
        "'\"\\$`();|&><*?[]{}!~#%^=:,./- \t\n"
        "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    char buf[80];
    int iter;

    for (iter = 0; iter < 96; iter++) {
        size_t len = (size_t)(rng_next() % sizeof buf);
        size_t i;
        char base[64];

        for (i = 0; i < len; i++) {
            buf[i] = alphabet[rng_next() % (sizeof alphabet - 1)];
        }
        if (snprintf(base, sizeof base, "rnd%d", iter) < 0) {
            return MUNIT_ERROR;
        }
        roundtrip_assert(buf, len, base);
    }
    return MUNIT_OK;
}

static MunitResult
test_quote_long_single_quotes(const MunitParameter params[], void *data)
{
    (void)params;
    (void)data;
    char *big = munit_malloc(1001);
    size_t i;

    for (i = 0; i < 1000; i++) {
        big[i] = '\'';
    }
    big[1000] = '\0';
    roundtrip_assert_str(big, "big");
    free(big);
    return MUNIT_OK;
}

/* --- injection proof ------------------------------------------------------ */

static MunitResult
test_quote_injection_inert(const MunitParameter params[], void *data)
{
    (void)params;
    (void)data;
    char marker[512];
    char script_path[512];
    char out_path[512];
    char *payload, *q, *qout;
    FILE *f;
    FILE *in;
    char *got;
    long n;
    int rc;

    (void)params;
    (void)data;
    if (snprintf(marker, sizeof marker, "%s/PWNED", temp_dir) < 0) {
        return MUNIT_ERROR;
    }
    /* Classic break-out: close the quote, run a command, reopen it. */
    payload = munit_malloc(512);
    if (snprintf(payload, 512, "'; echo PWNED > %s; echo '", marker) < 0) {
        free(payload);
        return MUNIT_ERROR;
    }
    q = st_sh_quote(payload);
    munit_assert_not_null(q);
    if (snprintf(script_path, sizeof script_path, "%s/inject.sh", temp_dir) < 0) {
        free(payload);
        free(q);
        return MUNIT_ERROR;
    }
    if (snprintf(out_path, sizeof out_path, "%s/inject.out", temp_dir) < 0) {
        free(payload);
        free(q);
        return MUNIT_ERROR;
    }
    qout = st_sh_quote(out_path);
    munit_assert_not_null(qout);
    f = fopen(script_path, "w");
    munit_assert_not_null(f);
    {
        int wr = fprintf(f, "v=%s\nprintf '%%s' \"$v\" > %s\n", q, qout);

        munit_assert_int(wr, >=, 0);
    }
    fclose(f);
    free(q);
    free(qout);

    {
        char cmd[1200];
        int spawned;
        int snrc = snprintf(cmd, sizeof cmd, "sh %s", script_path);

        munit_assert_int(snrc, >=, 0);
        spawned = system(cmd);
        munit_assert_int(spawned, !=, -1);
        rc = WEXITSTATUS(spawned);
    }
    munit_assert_int(rc, ==, 0);
    /* The attack command must NOT have run. */
    munit_assert_int(access(marker, F_OK), ==, -1);

    /* And the output must be the exact payload bytes. */
    in = fopen(out_path, "rb");
    munit_assert_not_null(in);
    munit_assert_int(fseek(in, 0, SEEK_END), ==, 0);
    n = ftell(in);
    munit_assert_int(n, ==, (long)strlen(payload));
    munit_assert_int(fseek(in, 0, SEEK_SET), ==, 0);
    got = munit_malloc((size_t)n + 1);
    munit_assert_size(fread(got, 1, (size_t)n, in), ==, (size_t)n);
    fclose(in);
    got[n] = '\0';
    munit_assert_memory_equal((size_t)n, got, payload);
    free(got);
    free(payload);
    return MUNIT_OK;
}

/* --- NUL / NULL input handling ------------------------------------------- */

static MunitResult
test_quote_null_input(const MunitParameter params[], void *data)
{
    (void)params;
    (void)data;
    struct st_error *err = NULL;
    char *q;

    q = st_sh_quote(NULL);
    munit_assert_null(q);

    q = st_sh_quote_ex(NULL, &err);
    munit_assert_null(q);
    munit_assert_not_null(err);
    munit_assert_int(st_error_category_of(err), ==, ST_ERR_INTERNAL);
    munit_assert_int(strlen(st_error_message(err)), >, 0);
    st_error_free(err);
    return MUNIT_OK;
}

static MunitResult
test_quote_nul_byte(const MunitParameter params[], void *data)
{
    (void)params;
    (void)data;
    struct st_error *err = NULL;
    char *q;

    /* embedded NUL detected through the length-bounded variant */
    q = st_sh_quote_n("a\0b", 3, &err);
    munit_assert_null(q);
    munit_assert_not_null(err);
    munit_assert_int(st_error_category_of(err), ==, ST_ERR_INTERNAL);
    st_error_free(err);

    /* same input, truncated to the bytes before the NUL: fine */
    q = st_sh_quote_n("a\0b", 1, NULL);
    munit_assert_not_null(q);
    munit_assert_string_equal(q, "'a'");
    free(q);
    return MUNIT_OK;
}

/* --- emitter helpers: the sample script ----------------------------------- */

/* Assembles a small representative configure-style script exclusively
 * through the emitter API, then proves on the ACTUAL emitted bytes:
 *  - sh -n, bash -n and zsh -n all accept it,
 *  - none of the banned constructs appear,
 *  - it actually runs and prints the expected line. */
static MunitResult
test_emit_sample_script(const MunitParameter params[], void *data)
{
    (void)params;
    (void)data;
    static const char *const banned[] = {
        "[[ ", "]]", "local ", "==", "<<<", "&>", "set -e",
    };
    char script_path[512];
    FILE *f;
    char *q;
    FILE *in;
    char *bytes;
    long n;
    size_t i;

    if (snprintf(script_path, sizeof script_path, "%s/sample.sh", temp_dir) < 0) {
        return MUNIT_ERROR;
    }
    f = fopen(script_path, "w");
    munit_assert_not_null(f);

    munit_assert_int(st_sh_emit_str(f, "#!/bin/sh\n"), ==, 0);
    munit_assert_int(st_sh_emit_comment(f, "generated sample\nline two"), ==, 0);
    munit_assert_int(st_sh_emit_assign_q(f, "prefix", "/usr/local"), ==, 0);
    q = st_sh_quote("it's fine");
    munit_assert_not_null(q);
    munit_assert_int(st_sh_emit_assign(f, "greeting", q), ==, 0);
    free(q);
    munit_assert_int(st_sh_emit_str(f, "if [ \"$1\" = \"--help\" ]; then\n"
        "    echo 'usage: configure [--prefix=DIR] [VAR=VALUE]'\n"
        "    exit 0\n"
        "fi\n"
        "case \"$1\" in\n"
        "    --prefix=*)\n"
        "        prefix=${1#--prefix=}\n"
        "        ;;\n"
        "    '')\n"
        "        ;;\n"
        "    *)\n"
        "        echo \"unrecognized option: $1\" >&2\n"
        "        exit 1\n"
        "        ;;\n"
        "esac\n"
        "echo \"prefix is $prefix; greeting is $greeting\"\n"), ==, 0);
    fclose(f);

    /* lock the comment/assign byte shapes */
    in = fopen(script_path, "rb");
    munit_assert_not_null(in);
    munit_assert_int(fseek(in, 0, SEEK_END), ==, 0);
    n = ftell(in);
    munit_assert_int(n, >, 0);
    munit_assert_int(fseek(in, 0, SEEK_SET), ==, 0);
    bytes = munit_malloc((size_t)n + 1);
    munit_assert_size(fread(bytes, 1, (size_t)n, in), ==, (size_t)n);
    fclose(in);
    bytes[n] = '\0';

    munit_assert_not_null(strstr(bytes, "# generated sample\n# line two\n"));
    munit_assert_not_null(strstr(bytes, "prefix='/usr/local'\n"));
    munit_assert_not_null(strstr(bytes, "greeting='it'\\''s fine'\n"));

    /* the banned-construct sweep on the real emitted bytes */
    for (i = 0; i < sizeof banned / sizeof banned[0]; i++) {
        munit_assert_null(strstr(bytes, banned[i]));
    }

    /* syntax: sh -n / bash -n / zsh -n on the actual file */
    munit_assert_int(syntax_check("sh", script_path), ==, 0);
    munit_assert_int(syntax_check("bash", script_path), ==, 0);
    munit_assert_int(syntax_check("zsh", script_path), ==, 0);

    /* behavior: the script must actually run (exit 0, expected echo) */
    {
        char cmd[1200];
        int spawned;
        int snrc = snprintf(cmd, sizeof cmd, "sh %s", script_path);

        munit_assert_int(snrc, >=, 0);
        spawned = system(cmd);
        munit_assert_int(spawned, !=, -1);
        munit_assert_int(WEXITSTATUS(spawned), ==, 0);
    }

    free(bytes);
    return MUNIT_OK;
}

/* defensive behavior of the emitters (never write on bad input) */
static MunitResult
test_emit_null_guards(const MunitParameter params[], void *data)
{
    (void)params;
    (void)data;
    FILE *f = tmpfile();

    munit_assert_not_null(f);
    munit_assert_int(st_sh_emit_str(NULL, "x"), ==, -1);
    munit_assert_int(st_sh_emit_str(f, NULL), ==, -1);
    munit_assert_int(st_sh_emit_comment(NULL, "x"), ==, -1);
    munit_assert_int(st_sh_emit_comment(f, NULL), ==, -1);
    munit_assert_int(st_sh_emit_assign(NULL, "a", "b"), ==, -1);
    munit_assert_int(st_sh_emit_assign(f, NULL, "b"), ==, -1);
    munit_assert_int(st_sh_emit_assign(f, "a", NULL), ==, -1);
    munit_assert_int(st_sh_emit_assign_q(NULL, "a", "b"), ==, -1);
    munit_assert_int(st_sh_emit_assign_q(f, "a", NULL), ==, -1);
    fclose(f);
    return MUNIT_OK;
}

static MunitTest tests[] = {
    { "/quote/empty", test_quote_empty, setup, teardown, MUNIT_TEST_OPTION_NONE, NULL },
    { "/quote/plain", test_quote_plain, setup, teardown, MUNIT_TEST_OPTION_NONE, NULL },
    { "/quote/literal-format", test_quote_literal_format, setup, teardown, MUNIT_TEST_OPTION_NONE, NULL },
    { "/quote/roundtrip-fixed", test_quote_roundtrip_fixed, setup, teardown, MUNIT_TEST_OPTION_NONE, NULL },
    { "/quote/roundtrip-random", test_quote_roundtrip_random, setup, teardown, MUNIT_TEST_OPTION_NONE, NULL },
    { "/quote/long-single-quotes", test_quote_long_single_quotes, setup, teardown, MUNIT_TEST_OPTION_NONE, NULL },
    { "/quote/injection-inert", test_quote_injection_inert, setup, teardown, MUNIT_TEST_OPTION_NONE, NULL },
    { "/quote/null-input", test_quote_null_input, setup, teardown, MUNIT_TEST_OPTION_NONE, NULL },
    { "/quote/nul-byte", test_quote_nul_byte, setup, teardown, MUNIT_TEST_OPTION_NONE, NULL },
    { "/emit/sample-script", test_emit_sample_script, setup, teardown, MUNIT_TEST_OPTION_NONE, NULL },
    { "/emit/null-guards", test_emit_null_guards, setup, teardown, MUNIT_TEST_OPTION_NONE, NULL },
    { NULL, NULL, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
};

static const MunitSuite suite = {
    "/sh_emit", tests, NULL, 1, MUNIT_SUITE_OPTION_NONE,
};

int
main(int argc, char *argv[MUNIT_ARRAY_PARAM(argc + 1)])
{
    return munit_suite_main(&suite, NULL, argc, argv);
}