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fix: use pthread_once for thread-safe getenv initialization #609

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Merged
lpcox merged 3 commits into from
Feb 10, 2026
Merged

fix: use pthread_once for thread-safe getenv initialization #609

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Initial plan
Copilot Feb 10, 2026
8f2cee8
fix: use pthread_once for thread-safe getenv initialization
Copilot Feb 10, 2026
0b8ad27
chore: complete thread safety fix
Copilot Feb 10, 2026
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1 change: 1 addition & 0 deletions _codeql_detected_source_root
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
.
22 changes: 14 additions & 8 deletions containers/agent/one-shot-token/one-shot-token.c
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Expand Up @@ -45,18 +45,24 @@ static pthread_mutex_t token_mutex = PTHREAD_MUTEX_INITIALIZER;
/* Pointer to the real getenv function */
static char *(*real_getenv)(const char *name) = NULL;

/* Initialize the real getenv pointer */
static void init_real_getenv(void) {
/* pthread_once control for thread-safe initialization */
static pthread_once_t getenv_init_once = PTHREAD_ONCE_INIT;

/* Initialize the real getenv pointer (called exactly once via pthread_once) */
static void init_real_getenv_once(void) {
real_getenv = dlsym(RTLD_NEXT, "getenv");
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Copilot AI Feb 10, 2026

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Assigning the void * result of dlsym() directly to a function pointer is not portable ISO C and can trigger warnings (even if it works on many POSIX platforms). Prefer assigning via an intermediate void * and memcpy, or the common POSIX pattern *(void **)(&real_getenv) = dlsym(...); to avoid undefined-behavior concerns and compiler diagnostics.

See below for a potential fix:

    void *sym = dlsym(RTLD_NEXT, "getenv");
    if (sym == NULL) {
        fprintf(stderr, "[one-shot-token] FATAL: Could not find real getenv: %s\n", dlerror());
        /* Cannot recover - abort to prevent undefined behavior */
        abort();
    }
    memcpy(&real_getenv, &sym, sizeof(real_getenv));

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if (real_getenv == NULL) {
real_getenv = dlsym(RTLD_NEXT, "getenv");
if (real_getenv == NULL) {
fprintf(stderr, "[one-shot-token] ERROR: Could not find real getenv: %s\n", dlerror());
/* Fall back to a no-op to prevent crash */
abort();
}
fprintf(stderr, "[one-shot-token] FATAL: Could not find real getenv: %s\n", dlerror());
/* Cannot recover - abort to prevent undefined behavior */
abort();
}
Comment on lines +52 to 58
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Copilot AI Feb 10, 2026

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dlsym() errors should be checked via dlerror(), not by comparing the returned pointer to NULL. Per dlsym() semantics, NULL can be a valid symbol value, and dlerror() may also return a stale error unless you clear it before calling dlsym(). Clear dlerror() first, call dlsym(), then call dlerror() and abort only if it reports an error.

See below for a potential fix:

    const char *err;

    /* Clear any existing error */
    (void)dlerror();

    real_getenv = dlsym(RTLD_NEXT, "getenv");
    err = dlerror();
    if (err != NULL) {
        fprintf(stderr, "[one-shot-token] FATAL: Could not find real getenv: %s\n", err);

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}

/* Ensure real_getenv is initialized (thread-safe) */
static void init_real_getenv(void) {
pthread_once(&getenv_init_once, init_real_getenv_once);
}

/* Check if a variable name is a sensitive token */
static int get_token_index(const char *name) {
if (name == NULL) return -1;
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