#include <time.h>

#include <string.h>

#define INITIAL_BUFFER_SIZE 64

#define MAX_BUFFER_SIZE 4096

/*

/* Process this segment (up to NUL or end of string) */

if (segment_len > 0) {

char *segment;

size_t buf_size;

char *buf;

size_t n;

/* Create null-terminated copy of this segment */

segment = (char *)mrb_malloc(mrb, (size_t)segment_len + 1);

/* Use mrb_temp_alloc for exception safety - GC will clean up on exception */

segment = (char *)mrb_temp_alloc(mrb, (size_t)segment_len + 1);

memcpy(segment, fmt_ptr, (size_t)segment_len);

segment[segment_len] = '\0';

/* Scan for %- patterns in the format string */

for (const char *p = segment; *p != '\0'; p++) {

if (p[0] == '%' && p[1] == '-') {

mrb_free(mrb, segment);

mrb_raisef(mrb, E_ARGUMENT_ERROR,

"strftime format flag '%-' not supported on this platform (use '%%#' on Windows)");

}

}

#endif

/* Allocate buffer for formatted output */

buf_size = INITIAL_BUFFER_SIZE;

buf = (char *)mrb_malloc(mrb, buf_size);

/* Try formatting; grow buffer if needed */

while (1) {

n = strftime(buf, buf_size, segment, tm);

/*

* strftime returns 0 if:

* 1. Buffer is too small (retry with larger buffer)

* 2. Format produces empty result (stop retrying)

* We distinguish by checking buffer size limit.

*/

if (n > 0 || buf_size >= MAX_BUFFER_SIZE) {

break;

}

/* Use mrb_temp_alloc with max size for exception safety */

buf = (char *)mrb_temp_alloc(mrb, MAX_BUFFER_SIZE);

/* Double buffer size and retry */

buf_size *= 2;

buf = (char *)mrb_realloc(mrb, buf, buf_size);

}

/* Try formatting with max buffer size */

n = strftime(buf, MAX_BUFFER_SIZE, segment, tm);

/* Append formatted output to result */

mrb_str_cat(mrb, result, buf, n);

mrb_free(mrb, buf);

mrb_free(mrb, segment);

}

/* If there was a NUL, append it to result and advance past it */