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Diffstat (limited to '')
| -rw-r--r-- | utf8.c | 340 |
1 files changed, 340 insertions, 0 deletions
@@ -0,0 +1,340 @@ +/* $OpenBSD: utf8.c,v 1.8 2018/08/21 13:56:27 schwarze Exp $ */ +/* + * Copyright (c) 2016 Ingo Schwarze <schwarze@openbsd.org> + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +/* + * Utility functions for multibyte-character handling, + * in particular to sanitize untrusted strings for terminal output. + */ + +#include "includes.h" + +#include <sys/types.h> +#ifdef HAVE_LANGINFO_H +# include <langinfo.h> +#endif +#include <limits.h> +#include <locale.h> +#include <stdarg.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS) +# include <vis.h> +#endif +#ifdef HAVE_WCHAR_H +# include <wchar.h> +#endif + +#include "utf8.h" + +static int dangerous_locale(void); +static int grow_dst(char **, size_t *, size_t, char **, size_t); +static int vasnmprintf(char **, size_t, int *, const char *, va_list); + + +/* + * For US-ASCII and UTF-8 encodings, we can safely recover from + * encoding errors and from non-printable characters. For any + * other encodings, err to the side of caution and abort parsing: + * For state-dependent encodings, recovery is impossible. + * For arbitrary encodings, replacement of non-printable + * characters would be non-trivial and too fragile. + * The comments indicate what nl_langinfo(CODESET) + * returns for US-ASCII on various operating systems. + */ + +static int +dangerous_locale(void) { + char *loc; + + loc = nl_langinfo(CODESET); + return strcmp(loc, "UTF-8") != 0 && + strcmp(loc, "US-ASCII") != 0 && /* OpenBSD */ + strcmp(loc, "ANSI_X3.4-1968") != 0 && /* Linux */ + strcmp(loc, "ISO8859-1") != 0 && /* AIX */ + strcmp(loc, "646") != 0 && /* Solaris, NetBSD */ + strcmp(loc, "") != 0; /* Solaris 6 */ +} + +static int +grow_dst(char **dst, size_t *sz, size_t maxsz, char **dp, size_t need) +{ + char *tp; + size_t tsz; + + if (*dp + need < *dst + *sz) + return 0; + tsz = *sz + 128; + if (tsz > maxsz) + tsz = maxsz; + if ((tp = recallocarray(*dst, *sz, tsz, 1)) == NULL) + return -1; + *dp = tp + (*dp - *dst); + *dst = tp; + *sz = tsz; + return 0; +} + +/* + * The following two functions limit the number of bytes written, + * including the terminating '\0', to sz. Unless wp is NULL, + * they limit the number of display columns occupied to *wp. + * Whichever is reached first terminates the output string. + * To stay close to the standard interfaces, they return the number of + * non-NUL bytes that would have been written if both were unlimited. + * If wp is NULL, newline, carriage return, and tab are allowed; + * otherwise, the actual number of columns occupied by what was + * written is returned in *wp. + */ + +static int +vasnmprintf(char **str, size_t maxsz, int *wp, const char *fmt, va_list ap) +{ + char *src; /* Source string returned from vasprintf. */ + char *sp; /* Pointer into src. */ + char *dst; /* Destination string to be returned. */ + char *dp; /* Pointer into dst. */ + char *tp; /* Temporary pointer for dst. */ + size_t sz; /* Number of bytes allocated for dst. */ + wchar_t wc; /* Wide character at sp. */ + int len; /* Number of bytes in the character at sp. */ + int ret; /* Number of bytes needed to format src. */ + int width; /* Display width of the character wc. */ + int total_width, max_width, print; + + src = NULL; + if ((ret = vasprintf(&src, fmt, ap)) <= 0) + goto fail; + + sz = strlen(src) + 1; + if ((dst = malloc(sz)) == NULL) { + free(src); + ret = -1; + goto fail; + } + + if (maxsz > INT_MAX) + maxsz = INT_MAX; + + sp = src; + dp = dst; + ret = 0; + print = 1; + total_width = 0; + max_width = wp == NULL ? INT_MAX : *wp; + while (*sp != '\0') { + if ((len = mbtowc(&wc, sp, MB_CUR_MAX)) == -1) { + (void)mbtowc(NULL, NULL, MB_CUR_MAX); + if (dangerous_locale()) { + ret = -1; + break; + } + len = 1; + width = -1; + } else if (wp == NULL && + (wc == L'\n' || wc == L'\r' || wc == L'\t')) { + /* + * Don't use width uninitialized; the actual + * value doesn't matter because total_width + * is only returned for wp != NULL. + */ + width = 0; + } else if ((width = wcwidth(wc)) == -1 && + dangerous_locale()) { + ret = -1; + break; + } + + /* Valid, printable character. */ + + if (width >= 0) { + if (print && (dp - dst >= (int)maxsz - len || + total_width > max_width - width)) + print = 0; + if (print) { + if (grow_dst(&dst, &sz, maxsz, + &dp, len) == -1) { + ret = -1; + break; + } + total_width += width; + memcpy(dp, sp, len); + dp += len; + } + sp += len; + if (ret >= 0) + ret += len; + continue; + } + + /* Escaping required. */ + + while (len > 0) { + if (print && (dp - dst >= (int)maxsz - 4 || + total_width > max_width - 4)) + print = 0; + if (print) { + if (grow_dst(&dst, &sz, maxsz, + &dp, 4) == -1) { + ret = -1; + break; + } + tp = vis(dp, *sp, VIS_OCTAL | VIS_ALL, 0); + width = tp - dp; + total_width += width; + dp = tp; + } else + width = 4; + len--; + sp++; + if (ret >= 0) + ret += width; + } + if (len > 0) + break; + } + free(src); + *dp = '\0'; + *str = dst; + if (wp != NULL) + *wp = total_width; + + /* + * If the string was truncated by the width limit but + * would have fit into the size limit, the only sane way + * to report the problem is using the return value, such + * that the usual idiom "if (ret < 0 || ret >= sz) error" + * works as expected. + */ + + if (ret < (int)maxsz && !print) + ret = -1; + return ret; + +fail: + if (wp != NULL) + *wp = 0; + if (ret == 0) { + *str = src; + return 0; + } else { + *str = NULL; + return -1; + } +} + +int +snmprintf(char *str, size_t sz, int *wp, const char *fmt, ...) +{ + va_list ap; + char *cp; + int ret; + + va_start(ap, fmt); + ret = vasnmprintf(&cp, sz, wp, fmt, ap); + va_end(ap); + if (cp != NULL) { + (void)strlcpy(str, cp, sz); + free(cp); + } else + *str = '\0'; + return ret; +} + +/* + * To stay close to the standard interfaces, the following functions + * return the number of non-NUL bytes written. + */ + +int +vfmprintf(FILE *stream, const char *fmt, va_list ap) +{ + char *str; + int ret; + + if ((ret = vasnmprintf(&str, INT_MAX, NULL, fmt, ap)) < 0) + return -1; + if (fputs(str, stream) == EOF) + ret = -1; + free(str); + return ret; +} + +int +fmprintf(FILE *stream, const char *fmt, ...) +{ + va_list ap; + int ret; + + va_start(ap, fmt); + ret = vfmprintf(stream, fmt, ap); + va_end(ap); + return ret; +} + +int +mprintf(const char *fmt, ...) +{ + va_list ap; + int ret; + + va_start(ap, fmt); + ret = vfmprintf(stdout, fmt, ap); + va_end(ap); + return ret; +} + +/* + * Set up libc for multibyte output in the user's chosen locale. + * + * XXX: we are known to have problems with Turkish (i/I confusion) so we + * deliberately fall back to the C locale for now. Longer term we should + * always prefer to select C.[encoding] if possible, but there's no + * standardisation in locales between systems, so we'll need to survey + * what's out there first. + */ +void +msetlocale(void) +{ + const char *vars[] = { "LC_ALL", "LC_CTYPE", "LANG", NULL }; + char *cp; + int i; + + /* + * We can't yet cope with dotless/dotted I in Turkish locales, + * so fall back to the C locale for these. + */ + for (i = 0; vars[i] != NULL; i++) { + if ((cp = getenv(vars[i])) == NULL) + continue; + if (strncasecmp(cp, "TR", 2) != 0) + break; + /* + * If we're in a UTF-8 locale then prefer to use + * the C.UTF-8 locale (or equivalent) if it exists. + */ + if ((strcasestr(cp, "UTF-8") != NULL || + strcasestr(cp, "UTF8") != NULL) && + (setlocale(LC_CTYPE, "C.UTF-8") != NULL || + setlocale(LC_CTYPE, "POSIX.UTF-8") != NULL)) + return; + setlocale(LC_CTYPE, "C"); + return; + } + /* We can handle this locale */ + setlocale(LC_CTYPE, ""); +} |