/* * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the OpenSSL license (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy * in the file LICENSE in the source distribution or at * https://www.openssl.org/source/license.html */ #include #include #include #include "internal/cryptlib_int.h" #include "internal/err.h" #include "internal/err_int.h" #include #include #include #include #include #include #include "internal/thread_once.h" static int err_load_strings(const ERR_STRING_DATA *str); static void ERR_STATE_free(ERR_STATE *s); #ifndef OPENSSL_NO_ERR static ERR_STRING_DATA ERR_str_libraries[] = { {ERR_PACK(ERR_LIB_NONE, 0, 0), "unknown library"}, {ERR_PACK(ERR_LIB_SYS, 0, 0), "system library"}, {ERR_PACK(ERR_LIB_BN, 0, 0), "bignum routines"}, {ERR_PACK(ERR_LIB_RSA, 0, 0), "rsa routines"}, {ERR_PACK(ERR_LIB_DH, 0, 0), "Diffie-Hellman routines"}, {ERR_PACK(ERR_LIB_EVP, 0, 0), "digital envelope routines"}, {ERR_PACK(ERR_LIB_BUF, 0, 0), "memory buffer routines"}, {ERR_PACK(ERR_LIB_OBJ, 0, 0), "object identifier routines"}, {ERR_PACK(ERR_LIB_PEM, 0, 0), "PEM routines"}, {ERR_PACK(ERR_LIB_DSA, 0, 0), "dsa routines"}, {ERR_PACK(ERR_LIB_X509, 0, 0), "x509 certificate routines"}, {ERR_PACK(ERR_LIB_ASN1, 0, 0), "asn1 encoding routines"}, {ERR_PACK(ERR_LIB_CONF, 0, 0), "configuration file routines"}, {ERR_PACK(ERR_LIB_CRYPTO, 0, 0), "common libcrypto routines"}, {ERR_PACK(ERR_LIB_EC, 0, 0), "elliptic curve routines"}, {ERR_PACK(ERR_LIB_ECDSA, 0, 0), "ECDSA routines"}, {ERR_PACK(ERR_LIB_ECDH, 0, 0), "ECDH routines"}, {ERR_PACK(ERR_LIB_SSL, 0, 0), "SSL routines"}, {ERR_PACK(ERR_LIB_BIO, 0, 0), "BIO routines"}, {ERR_PACK(ERR_LIB_PKCS7, 0, 0), "PKCS7 routines"}, {ERR_PACK(ERR_LIB_X509V3, 0, 0), "X509 V3 routines"}, {ERR_PACK(ERR_LIB_PKCS12, 0, 0), "PKCS12 routines"}, {ERR_PACK(ERR_LIB_RAND, 0, 0), "random number generator"}, {ERR_PACK(ERR_LIB_DSO, 0, 0), "DSO support routines"}, {ERR_PACK(ERR_LIB_TS, 0, 0), "time stamp routines"}, {ERR_PACK(ERR_LIB_ENGINE, 0, 0), "engine routines"}, {ERR_PACK(ERR_LIB_OCSP, 0, 0), "OCSP routines"}, {ERR_PACK(ERR_LIB_UI, 0, 0), "UI routines"}, {ERR_PACK(ERR_LIB_FIPS, 0, 0), "FIPS routines"}, {ERR_PACK(ERR_LIB_CMS, 0, 0), "CMS routines"}, {ERR_PACK(ERR_LIB_HMAC, 0, 0), "HMAC routines"}, {ERR_PACK(ERR_LIB_CT, 0, 0), "CT routines"}, {ERR_PACK(ERR_LIB_ASYNC, 0, 0), "ASYNC routines"}, {ERR_PACK(ERR_LIB_KDF, 0, 0), "KDF routines"}, {ERR_PACK(ERR_LIB_OSSL_STORE, 0, 0), "STORE routines"}, {0, NULL}, }; static ERR_STRING_DATA ERR_str_functs[] = { {ERR_PACK(0, SYS_F_FOPEN, 0), "fopen"}, {ERR_PACK(0, SYS_F_CONNECT, 0), "connect"}, {ERR_PACK(0, SYS_F_GETSERVBYNAME, 0), "getservbyname"}, {ERR_PACK(0, SYS_F_SOCKET, 0), "socket"}, {ERR_PACK(0, SYS_F_IOCTLSOCKET, 0), "ioctlsocket"}, {ERR_PACK(0, SYS_F_BIND, 0), "bind"}, {ERR_PACK(0, SYS_F_LISTEN, 0), "listen"}, {ERR_PACK(0, SYS_F_ACCEPT, 0), "accept"}, # ifdef OPENSSL_SYS_WINDOWS {ERR_PACK(0, SYS_F_WSASTARTUP, 0), "WSAstartup"}, # endif {ERR_PACK(0, SYS_F_OPENDIR, 0), "opendir"}, {ERR_PACK(0, SYS_F_FREAD, 0), "fread"}, {ERR_PACK(0, SYS_F_GETADDRINFO, 0), "getaddrinfo"}, {ERR_PACK(0, SYS_F_GETNAMEINFO, 0), "getnameinfo"}, {ERR_PACK(0, SYS_F_SETSOCKOPT, 0), "setsockopt"}, {ERR_PACK(0, SYS_F_GETSOCKOPT, 0), "getsockopt"}, {ERR_PACK(0, SYS_F_GETSOCKNAME, 0), "getsockname"}, {ERR_PACK(0, SYS_F_GETHOSTBYNAME, 0), "gethostbyname"}, {ERR_PACK(0, SYS_F_FFLUSH, 0), "fflush"}, {ERR_PACK(0, SYS_F_OPEN, 0), "open"}, {ERR_PACK(0, SYS_F_CLOSE, 0), "close"}, {ERR_PACK(0, SYS_F_IOCTL, 0), "ioctl"}, {ERR_PACK(0, SYS_F_STAT, 0), "stat"}, {ERR_PACK(0, SYS_F_FCNTL, 0), "fcntl"}, {0, NULL}, }; static ERR_STRING_DATA ERR_str_reasons[] = { {ERR_R_SYS_LIB, "system lib"}, {ERR_R_BN_LIB, "BN lib"}, {ERR_R_RSA_LIB, "RSA lib"}, {ERR_R_DH_LIB, "DH lib"}, {ERR_R_EVP_LIB, "EVP lib"}, {ERR_R_BUF_LIB, "BUF lib"}, {ERR_R_OBJ_LIB, "OBJ lib"}, {ERR_R_PEM_LIB, "PEM lib"}, {ERR_R_DSA_LIB, "DSA lib"}, {ERR_R_X509_LIB, "X509 lib"}, {ERR_R_ASN1_LIB, "ASN1 lib"}, {ERR_R_EC_LIB, "EC lib"}, {ERR_R_BIO_LIB, "BIO lib"}, {ERR_R_PKCS7_LIB, "PKCS7 lib"}, {ERR_R_X509V3_LIB, "X509V3 lib"}, {ERR_R_ENGINE_LIB, "ENGINE lib"}, {ERR_R_UI_LIB, "UI lib"}, {ERR_R_OSSL_STORE_LIB, "STORE lib"}, {ERR_R_ECDSA_LIB, "ECDSA lib"}, {ERR_R_NESTED_ASN1_ERROR, "nested asn1 error"}, {ERR_R_MISSING_ASN1_EOS, "missing asn1 eos"}, {ERR_R_FATAL, "fatal"}, {ERR_R_MALLOC_FAILURE, "malloc failure"}, {ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED, "called a function you should not call"}, {ERR_R_PASSED_NULL_PARAMETER, "passed a null parameter"}, {ERR_R_INTERNAL_ERROR, "internal error"}, {ERR_R_DISABLED, "called a function that was disabled at compile-time"}, {ERR_R_INIT_FAIL, "init fail"}, {ERR_R_OPERATION_FAIL, "operation fail"}, {0, NULL}, }; #endif static CRYPTO_ONCE err_init = CRYPTO_ONCE_STATIC_INIT; static int set_err_thread_local; static CRYPTO_THREAD_LOCAL err_thread_local; static CRYPTO_ONCE err_string_init = CRYPTO_ONCE_STATIC_INIT; static CRYPTO_RWLOCK *err_string_lock; static ERR_STRING_DATA *int_err_get_item(const ERR_STRING_DATA *); /* * The internal state */ static LHASH_OF(ERR_STRING_DATA) *int_error_hash = NULL; static int int_err_library_number = ERR_LIB_USER; static unsigned long get_error_values(int inc, int top, const char **file, int *line, const char **data, int *flags); static unsigned long err_string_data_hash(const ERR_STRING_DATA *a) { unsigned long ret, l; l = a->error; ret = l ^ ERR_GET_LIB(l) ^ ERR_GET_FUNC(l); return (ret ^ ret % 19 * 13); } static int err_string_data_cmp(const ERR_STRING_DATA *a, const ERR_STRING_DATA *b) { if (a->error == b->error) return 0; return a->error > b->error ? 1 : -1; } static ERR_STRING_DATA *int_err_get_item(const ERR_STRING_DATA *d) { ERR_STRING_DATA *p = NULL; CRYPTO_THREAD_read_lock(err_string_lock); p = lh_ERR_STRING_DATA_retrieve(int_error_hash, d); CRYPTO_THREAD_unlock(err_string_lock); return p; } #ifndef OPENSSL_NO_ERR # define NUM_SYS_STR_REASONS 127 # define LEN_SYS_STR_REASON 32 static ERR_STRING_DATA SYS_str_reasons[NUM_SYS_STR_REASONS + 1]; /* * SYS_str_reasons is filled with copies of strerror() results at * initialization. 'errno' values up to 127 should cover all usual errors, * others will be displayed numerically by ERR_error_string. It is crucial * that we have something for each reason code that occurs in * ERR_str_reasons, or bogus reason strings will be returned for SYSerr(), * which always gets an errno value and never one of those 'standard' reason * codes. */ static void build_SYS_str_reasons(void) { /* OPENSSL_malloc cannot be used here, use static storage instead */ static char strerror_tab[NUM_SYS_STR_REASONS][LEN_SYS_STR_REASON]; static int init = 1; int i; CRYPTO_THREAD_write_lock(err_string_lock); if (!init) { CRYPTO_THREAD_unlock(err_string_lock); return; } for (i = 1; i <= NUM_SYS_STR_REASONS; i++) { ERR_STRING_DATA *str = &SYS_str_reasons[i - 1]; str->error = ERR_PACK(ERR_LIB_SYS, 0, i); if (str->string == NULL) { char (*dest)[LEN_SYS_STR_REASON] = &(strerror_tab[i - 1]); if (openssl_strerror_r(i, *dest, sizeof(*dest))) str->string = *dest; } if (str->string == NULL) str->string = "unknown"; } /* * Now we still have SYS_str_reasons[NUM_SYS_STR_REASONS] = {0, NULL}, as * required by ERR_load_strings. */ init = 0; CRYPTO_THREAD_unlock(err_string_lock); err_load_strings(SYS_str_reasons); } #endif #define err_clear_data(p,i) \ do { \ if ((p)->err_data_flags[i] & ERR_TXT_MALLOCED) \ { \ OPENSSL_free((p)->err_data[i]); \ (p)->err_data[i]=NULL; \ } \ (p)->err_data_flags[i]=0; \ } while(0) #define err_clear(p,i) \ do { \ (p)->err_flags[i]=0; \ (p)->err_buffer[i]=0; \ err_clear_data(p,i); \ (p)->err_file[i]=NULL; \ (p)->err_line[i]= -1; \ } while(0) static void ERR_STATE_free(ERR_STATE *s) { int i; if (s == NULL) return; for (i = 0; i < ERR_NUM_ERRORS; i++) { err_clear_data(s, i); } OPENSSL_free(s); } DEFINE_RUN_ONCE_STATIC(do_err_strings_init) { OPENSSL_init_crypto(0, NULL); err_string_lock = CRYPTO_THREAD_glock_new("err_string"); int_error_hash = lh_ERR_STRING_DATA_new(err_string_data_hash, err_string_data_cmp); return err_string_lock != NULL && int_error_hash != NULL; } void err_cleanup(void) { if (set_err_thread_local != 0) CRYPTO_THREAD_cleanup_local(&err_thread_local); CRYPTO_THREAD_lock_free(err_string_lock); err_string_lock = NULL; lh_ERR_STRING_DATA_free(int_error_hash); int_error_hash = NULL; } /* * Legacy; pack in the library. */ static void err_patch(int lib, ERR_STRING_DATA *str) { unsigned long plib = ERR_PACK(lib, 0, 0); for (; str->error != 0; str++) str->error |= plib; } /* * Hash in |str| error strings. Assumes the URN_ONCE was done. */ static int err_load_strings(const ERR_STRING_DATA *str) { CRYPTO_THREAD_write_lock(err_string_lock); for (; str->error; str++) (void)lh_ERR_STRING_DATA_insert(int_error_hash, (ERR_STRING_DATA *)str); CRYPTO_THREAD_unlock(err_string_lock); return 1; } int ERR_load_ERR_strings(void) { #ifndef OPENSSL_NO_ERR if (!RUN_ONCE(&err_string_init, do_err_strings_init)) return 0; err_load_strings(ERR_str_libraries); err_load_strings(ERR_str_reasons); err_patch(ERR_LIB_SYS, ERR_str_functs); err_load_strings(ERR_str_functs); build_SYS_str_reasons(); #endif return 1; } int ERR_load_strings(int lib, ERR_STRING_DATA *str) { if (ERR_load_ERR_strings() == 0) return 0; err_patch(lib, str); err_load_strings(str); return 1; } int ERR_load_strings_const(const ERR_STRING_DATA *str) { if (ERR_load_ERR_strings() == 0) return 0; err_load_strings(str); return 1; } int ERR_unload_strings(int lib, ERR_STRING_DATA *str) { if (!RUN_ONCE(&err_string_init, do_err_strings_init)) return 0; CRYPTO_THREAD_write_lock(err_string_lock); /* * We don't need to ERR_PACK the lib, since that was done (to * the table) when it was loaded. */ for (; str->error; str++) (void)lh_ERR_STRING_DATA_delete(int_error_hash, str); CRYPTO_THREAD_unlock(err_string_lock); return 1; } void err_free_strings_int(void) { if (!RUN_ONCE(&err_string_init, do_err_strings_init)) return; } /********************************************************/ void ERR_put_error(int lib, int func, int reason, const char *file, int line) { ERR_STATE *es; #ifdef _OSD_POSIX /* * In the BS2000-OSD POSIX subsystem, the compiler generates path names * in the form "*POSIX(/etc/passwd)". This dirty hack strips them to * something sensible. @@@ We shouldn't modify a const string, though. */ if (strncmp(file, "*POSIX(", sizeof("*POSIX(") - 1) == 0) { char *end; /* Skip the "*POSIX(" prefix */ file += sizeof("*POSIX(") - 1; end = &file[strlen(file) - 1]; if (*end == ')') *end = '\0'; /* Optional: use the basename of the path only. */ if ((end = strrchr(file, '/')) != NULL) file = &end[1]; } #endif es = ERR_get_state(); if (es == NULL) return; es->top = (es->top + 1) % ERR_NUM_ERRORS; if (es->top == es->bottom) es->bottom = (es->bottom + 1) % ERR_NUM_ERRORS; es->err_flags[es->top] = 0; es->err_buffer[es->top] = ERR_PACK(lib, func, reason); es->err_file[es->top] = file; es->err_line[es->top] = line; err_clear_data(es, es->top); } void ERR_clear_error(void) { int i; ERR_STATE *es; es = ERR_get_state(); if (es == NULL) return; for (i = 0; i < ERR_NUM_ERRORS; i++) { err_clear(es, i); } es->top = es->bottom = 0; } unsigned long ERR_get_error(void) { return (get_error_values(1, 0, NULL, NULL, NULL, NULL)); } unsigned long ERR_get_error_line(const char **file, int *line) { return (get_error_values(1, 0, file, line, NULL, NULL)); } unsigned long ERR_get_error_line_data(const char **file, int *line, const char **data, int *flags) { return (get_error_values(1, 0, file, line, data, flags)); } unsigned long ERR_peek_error(void) { return (get_error_values(0, 0, NULL, NULL, NULL, NULL)); } unsigned long ERR_peek_error_line(const char **file, int *line) { return (get_error_values(0, 0, file, line, NULL, NULL)); } unsigned long ERR_peek_error_line_data(const char **file, int *line, const char **data, int *flags) { return (get_error_values(0, 0, file, line, data, flags)); } unsigned long ERR_peek_last_error(void) { return (get_error_values(0, 1, NULL, NULL, NULL, NULL)); } unsigned long ERR_peek_last_error_line(const char **file, int *line) { return (get_error_values(0, 1, file, line, NULL, NULL)); } unsigned long ERR_peek_last_error_line_data(const char **file, int *line, const char **data, int *flags) { return (get_error_values(0, 1, file, line, data, flags)); } static unsigned long get_error_values(int inc, int top, const char **file, int *line, const char **data, int *flags) { int i = 0; ERR_STATE *es; unsigned long ret; es = ERR_get_state(); if (es == NULL) return 0; if (inc && top) { if (file) *file = ""; if (line) *line = 0; if (data) *data = ""; if (flags) *flags = 0; return ERR_R_INTERNAL_ERROR; } if (es->bottom == es->top) return 0; if (top) i = es->top; /* last error */ else i = (es->bottom + 1) % ERR_NUM_ERRORS; /* first error */ ret = es->err_buffer[i]; if (inc) { es->bottom = i; es->err_buffer[i] = 0; } if ((file != NULL) && (line != NULL)) { if (es->err_file[i] == NULL) { *file = "NA"; if (line != NULL) *line = 0; } else { *file = es->err_file[i]; if (line != NULL) *line = es->err_line[i]; } } if (data == NULL) { if (inc) { err_clear_data(es, i); } } else { if (es->err_data[i] == NULL) { *data = ""; if (flags != NULL) *flags = 0; } else { *data = es->err_data[i]; if (flags != NULL) *flags = es->err_data_flags[i]; } } return ret; } void ERR_error_string_n(unsigned long e, char *buf, size_t len) { char lsbuf[64], fsbuf[64], rsbuf[64]; const char *ls, *fs, *rs; unsigned long l, f, r; if (len == 0) return; l = ERR_GET_LIB(e); f = ERR_GET_FUNC(e); r = ERR_GET_REASON(e); ls = ERR_lib_error_string(e); fs = ERR_func_error_string(e); rs = ERR_reason_error_string(e); if (ls == NULL) BIO_snprintf(lsbuf, sizeof(lsbuf), "lib(%lu)", l); if (fs == NULL) BIO_snprintf(fsbuf, sizeof(fsbuf), "func(%lu)", f); if (rs == NULL) BIO_snprintf(rsbuf, sizeof(rsbuf), "reason(%lu)", r); BIO_snprintf(buf, len, "error:%08lX:%s:%s:%s", e, ls ? ls : lsbuf, fs ? fs : fsbuf, rs ? rs : rsbuf); if (strlen(buf) == len - 1) { /* * output may be truncated; make sure we always have 5 * colon-separated fields, i.e. 4 colons ... */ #define NUM_COLONS 4 if (len > NUM_COLONS) { /* ... if possible */ int i; char *s = buf; for (i = 0; i < NUM_COLONS; i++) { char *colon = strchr(s, ':'); if (colon == NULL || colon > &buf[len - 1] - NUM_COLONS + i) { /* * set colon no. i at last possible position (buf[len-1] * is the terminating 0) */ colon = &buf[len - 1] - NUM_COLONS + i; *colon = ':'; } s = colon + 1; } } } } /* * ERR_error_string_n should be used instead for ret != NULL as * ERR_error_string cannot know how large the buffer is */ char *ERR_error_string(unsigned long e, char *ret) { static char buf[256]; if (ret == NULL) ret = buf; ERR_error_string_n(e, ret, 256); return ret; } const char *ERR_lib_error_string(unsigned long e) { ERR_STRING_DATA d, *p; unsigned long l; if (!RUN_ONCE(&err_string_init, do_err_strings_init)) { return NULL; } l = ERR_GET_LIB(e); d.error = ERR_PACK(l, 0, 0); p = int_err_get_item(&d); return ((p == NULL) ? NULL : p->string); } const char *ERR_func_error_string(unsigned long e) { ERR_STRING_DATA d, *p; unsigned long l, f; if (!RUN_ONCE(&err_string_init, do_err_strings_init)) { return NULL; } l = ERR_GET_LIB(e); f = ERR_GET_FUNC(e); d.error = ERR_PACK(l, f, 0); p = int_err_get_item(&d); return ((p == NULL) ? NULL : p->string); } const char *ERR_reason_error_string(unsigned long e) { ERR_STRING_DATA d, *p = NULL; unsigned long l, r; if (!RUN_ONCE(&err_string_init, do_err_strings_init)) { return NULL; } l = ERR_GET_LIB(e); r = ERR_GET_REASON(e); d.error = ERR_PACK(l, 0, r); p = int_err_get_item(&d); if (!p) { d.error = ERR_PACK(0, 0, r); p = int_err_get_item(&d); } return ((p == NULL) ? NULL : p->string); } void err_delete_thread_state(void) { ERR_STATE *state = CRYPTO_THREAD_get_local(&err_thread_local); if (state == NULL) return; CRYPTO_THREAD_set_local(&err_thread_local, NULL); ERR_STATE_free(state); } #if OPENSSL_API_COMPAT < 0x10100000L void ERR_remove_thread_state(void *dummy) { } #endif #if OPENSSL_API_COMPAT < 0x10000000L void ERR_remove_state(unsigned long pid) { } #endif DEFINE_RUN_ONCE_STATIC(err_do_init) { set_err_thread_local = 1; return CRYPTO_THREAD_init_local(&err_thread_local, NULL); } ERR_STATE *ERR_get_state(void) { ERR_STATE *state = NULL; if (!RUN_ONCE(&err_init, err_do_init)) return NULL; state = CRYPTO_THREAD_get_local(&err_thread_local); if (state == NULL) { state = OPENSSL_zalloc(sizeof(*state)); if (state == NULL) return NULL; if (!ossl_init_thread_start(OPENSSL_INIT_THREAD_ERR_STATE) || !CRYPTO_THREAD_set_local(&err_thread_local, state)) { ERR_STATE_free(state); return NULL; } /* Ignore failures from these */ OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CRYPTO_STRINGS, NULL); } return state; } int ERR_get_next_error_library(void) { int ret; if (!RUN_ONCE(&err_string_init, do_err_strings_init)) { return 0; } CRYPTO_THREAD_write_lock(err_string_lock); ret = int_err_library_number++; CRYPTO_THREAD_unlock(err_string_lock); return ret; } void ERR_set_error_data(char *data, int flags) { ERR_STATE *es; int i; es = ERR_get_state(); if (es == NULL) return; i = es->top; err_clear_data(es, i); es->err_data[i] = data; es->err_data_flags[i] = flags; } void ERR_add_error_data(int num, ...) { va_list args; va_start(args, num); ERR_add_error_vdata(num, args); va_end(args); } void ERR_add_error_vdata(int num, va_list args) { int i, n, s; char *str, *p, *a; s = 80; str = OPENSSL_malloc(s + 1); if (str == NULL) return; str[0] = '\0'; n = 0; for (i = 0; i < num; i++) { a = va_arg(args, char *); if (a == NULL) a = ""; n += strlen(a); if (n > s) { s = n + 20; p = OPENSSL_realloc(str, s + 1); if (p == NULL) { OPENSSL_free(str); return; } str = p; } OPENSSL_strlcat(str, a, (size_t)s + 1); } ERR_set_error_data(str, ERR_TXT_MALLOCED | ERR_TXT_STRING); } int ERR_set_mark(void) { ERR_STATE *es; es = ERR_get_state(); if (es == NULL) return 0; if (es->bottom == es->top) return 0; es->err_flags[es->top] |= ERR_FLAG_MARK; return 1; } int ERR_pop_to_mark(void) { ERR_STATE *es; es = ERR_get_state(); if (es == NULL) return 0; while (es->bottom != es->top && (es->err_flags[es->top] & ERR_FLAG_MARK) == 0) { err_clear(es, es->top); es->top = es->top > 0 ? es->top - 1 : ERR_NUM_ERRORS - 1; } if (es->bottom == es->top) return 0; es->err_flags[es->top] &= ~ERR_FLAG_MARK; return 1; } int ERR_clear_last_mark(void) { ERR_STATE *es; int top; es = ERR_get_state(); if (es == NULL) return 0; top = es->top; while (es->bottom != top && (es->err_flags[top] & ERR_FLAG_MARK) == 0) { top = top > 0 ? top - 1 : ERR_NUM_ERRORS - 1; } if (es->bottom == top) return 0; es->err_flags[top] &= ~ERR_FLAG_MARK; return 1; }