/* $NetBSD: ascmagic.c,v 1.1.1.15 2022/09/24 20:07:54 christos Exp $ */ /* * Copyright (c) Ian F. Darwin 1986-1995. * Software written by Ian F. Darwin and others; * maintained 1995-present by Christos Zoulas and others. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice immediately at the beginning of the file, without modification, * this list of conditions, and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * ASCII magic -- try to detect text encoding. * * Extensively modified by Eric Fischer in July, 2000, * to handle character codes other than ASCII on a unified basis. */ #include "file.h" #ifndef lint #if 0 FILE_RCSID("@(#)$File: ascmagic.c,v 1.110 2021/12/06 15:33:00 christos Exp $") #else __RCSID("$NetBSD: ascmagic.c,v 1.1.1.15 2022/09/24 20:07:54 christos Exp $"); #endif #endif /* lint */ #include "magic.h" #include #include #include #ifdef HAVE_UNISTD_H #include #endif #define MAXLINELEN 300 /* longest sane line length */ #define ISSPC(x) ((x) == ' ' || (x) == '\t' || (x) == '\r' || (x) == '\n' \ || (x) == 0x85 || (x) == '\f') private unsigned char *encode_utf8(unsigned char *, size_t, file_unichar_t *, size_t); private size_t trim_nuls(const unsigned char *, size_t); /* * Undo the NUL-termination kindly provided by process() * but leave at least one byte to look at */ private size_t trim_nuls(const unsigned char *buf, size_t nbytes) { while (nbytes > 1 && buf[nbytes - 1] == '\0') nbytes--; return nbytes; } protected int file_ascmagic(struct magic_set *ms, const struct buffer *b, int text) { file_unichar_t *ubuf = NULL; size_t ulen = 0; int rv = 1; struct buffer bb; const char *code = NULL; const char *code_mime = NULL; const char *type = NULL; bb = *b; bb.flen = trim_nuls(CAST(const unsigned char *, b->fbuf), b->flen); /* * Avoid trimming at an odd byte if the original buffer was evenly * sized; this avoids losing the last character on UTF-16 LE text */ if ((bb.flen & 1) && !(b->flen & 1)) bb.flen++; /* If file doesn't look like any sort of text, give up. */ if (file_encoding(ms, &bb, &ubuf, &ulen, &code, &code_mime, &type) == 0) rv = 0; else rv = file_ascmagic_with_encoding(ms, &bb, ubuf, ulen, code, type, text); free(ubuf); return rv; } protected int file_ascmagic_with_encoding(struct magic_set *ms, const struct buffer *b, file_unichar_t *ubuf, size_t ulen, const char *code, const char *type, int text) { struct buffer bb; const unsigned char *buf = CAST(const unsigned char *, b->fbuf); size_t nbytes = b->flen; unsigned char *utf8_buf = NULL, *utf8_end; size_t mlen, i, len; int rv = -1; int mime = ms->flags & MAGIC_MIME; int need_separator = 0; const char *subtype = NULL; int has_escapes = 0; int has_backspace = 0; int seen_cr = 0; int n_crlf = 0; int n_lf = 0; int n_cr = 0; int n_nel = 0; int executable = 0; size_t last_line_end = CAST(size_t, -1); size_t has_long_lines = 0; nbytes = trim_nuls(buf, nbytes); /* If we have fewer than 2 bytes, give up. */ if (nbytes <= 1) { rv = 0; goto done; } if (ulen > 0 && (ms->flags & MAGIC_NO_CHECK_SOFT) == 0) { /* Convert ubuf to UTF-8 and try text soft magic */ /* malloc size is a conservative overestimate; could be improved, or at least realloced after conversion. */ mlen = ulen * 6; if ((utf8_buf = CAST(unsigned char *, malloc(mlen))) == NULL) { file_oomem(ms, mlen); goto done; } if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen)) == NULL) goto done; buffer_init(&bb, b->fd, &b->st, utf8_buf, CAST(size_t, utf8_end - utf8_buf)); if ((rv = file_softmagic(ms, &bb, NULL, NULL, TEXTTEST, text)) == 0) rv = -1; else need_separator = 1; buffer_fini(&bb); if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) { rv = rv == -1 ? 0 : 1; goto done; } } if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) { rv = 0; goto done; } /* Now try to discover other details about the file. */ for (i = 0; i < ulen; i++) { if (ubuf[i] == '\n') { if (seen_cr) n_crlf++; else n_lf++; last_line_end = i; } else if (seen_cr) n_cr++; seen_cr = (ubuf[i] == '\r'); if (seen_cr) last_line_end = i; if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */ n_nel++; last_line_end = i; } /* If this line is _longer_ than MAXLINELEN, remember it. */ if (i > last_line_end + MAXLINELEN) { size_t ll = i - last_line_end; if (ll > has_long_lines) has_long_lines = ll; } if (ubuf[i] == '\033') has_escapes = 1; if (ubuf[i] == '\b') has_backspace = 1; } /* Beware, if the data has been truncated, the final CR could have been followed by a LF. If we have ms->bytes_max bytes, it indicates that the data might have been truncated, probably even before this function was called. */ if (seen_cr && nbytes < ms->bytes_max) n_cr++; if (strcmp(type, "binary") == 0) { rv = 0; goto done; } len = file_printedlen(ms); if (mime) { if ((mime & MAGIC_MIME_TYPE) != 0) { if (len) { /* * Softmagic printed something, we * are either done, or we need a separator */ if ((ms->flags & MAGIC_CONTINUE) == 0) { rv = 1; goto done; } if (need_separator && file_separator(ms) == -1) goto done; } else { if (file_printf(ms, "text/plain") == -1) goto done; } } } else { if (len) { switch (file_replace(ms, " text$", ", ")) { case 0: switch (file_replace(ms, " text executable$", ", ")) { case 0: if (file_printf(ms, ", ") == -1) goto done; break; case -1: goto done; default: executable = 1; break; } break; case -1: goto done; default: break; } } if (file_printf(ms, "%s", code) == -1) goto done; if (subtype) { if (file_printf(ms, " %s", subtype) == -1) goto done; } if (file_printf(ms, " %s", type) == -1) goto done; if (executable) if (file_printf(ms, " executable") == -1) goto done; if (has_long_lines) if (file_printf(ms, ", with very long lines (%" SIZE_T_FORMAT "u)", has_long_lines) == -1) goto done; /* * Only report line terminators if we find one other than LF, * or if we find none at all. */ if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) || (n_crlf != 0 || n_cr != 0 || n_nel != 0)) { if (file_printf(ms, ", with") == -1) goto done; if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) { if (file_printf(ms, " no") == -1) goto done; } else { if (n_crlf) { if (file_printf(ms, " CRLF") == -1) goto done; if (n_cr || n_lf || n_nel) if (file_printf(ms, ",") == -1) goto done; } if (n_cr) { if (file_printf(ms, " CR") == -1) goto done; if (n_lf || n_nel) if (file_printf(ms, ",") == -1) goto done; } if (n_lf) { if (file_printf(ms, " LF") == -1) goto done; if (n_nel) if (file_printf(ms, ",") == -1) goto done; } if (n_nel) if (file_printf(ms, " NEL") == -1) goto done; } if (file_printf(ms, " line terminators") == -1) goto done; } if (has_escapes) if (file_printf(ms, ", with escape sequences") == -1) goto done; if (has_backspace) if (file_printf(ms, ", with overstriking") == -1) goto done; } rv = 1; done: free(utf8_buf); return rv; } /* * Encode Unicode string as UTF-8, returning pointer to character * after end of string, or NULL if an invalid character is found. */ private unsigned char * encode_utf8(unsigned char *buf, size_t len, file_unichar_t *ubuf, size_t ulen) { size_t i; unsigned char *end = buf + len; for (i = 0; i < ulen; i++) { if (ubuf[i] <= 0x7f) { if (end - buf < 1) return NULL; *buf++ = CAST(unsigned char, ubuf[i]); continue; } if (ubuf[i] <= 0x7ff) { if (end - buf < 2) return NULL; *buf++ = CAST(unsigned char, (ubuf[i] >> 6) + 0xc0); goto out1; } if (ubuf[i] <= 0xffff) { if (end - buf < 3) return NULL; *buf++ = CAST(unsigned char, (ubuf[i] >> 12) + 0xe0); goto out2; } if (ubuf[i] <= 0x1fffff) { if (end - buf < 4) return NULL; *buf++ = CAST(unsigned char, (ubuf[i] >> 18) + 0xf0); goto out3; } if (ubuf[i] <= 0x3ffffff) { if (end - buf < 5) return NULL; *buf++ = CAST(unsigned char, (ubuf[i] >> 24) + 0xf8); goto out4; } if (ubuf[i] <= 0x7fffffff) { if (end - buf < 6) return NULL; *buf++ = CAST(unsigned char, (ubuf[i] >> 30) + 0xfc); goto out5; } /* Invalid character */ return NULL; out5: *buf++ = CAST(unsigned char, ((ubuf[i] >> 24) & 0x3f) + 0x80); out4: *buf++ = CAST(unsigned char, ((ubuf[i] >> 18) & 0x3f) + 0x80); out3: *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80); out2: *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80); out1: *buf++ = CAST(unsigned char, ((ubuf[i] >> 0) & 0x3f) + 0x80); } return buf; }