/* $OpenBSD: apprentice.c,v 1.3 1996/06/26 05:32:54 deraadt Exp $ */ /* * apprentice - make one pass through /etc/magic, learning its secrets. * * Copyright (c) Ian F. Darwin, 1987. * Written by Ian F. Darwin. * * This software is not subject to any license of the American Telephone * and Telegraph Company or of the Regents of the University of California. * * Permission is granted to anyone to use this software for any purpose on * any computer system, and to alter it and redistribute it freely, subject * to the following restrictions: * * 1. The author is not responsible for the consequences of use of this * software, no matter how awful, even if they arise from flaws in it. * * 2. The origin of this software must not be misrepresented, either by * explicit claim or by omission. Since few users ever read sources, * credits must appear in the documentation. * * 3. Altered versions must be plainly marked as such, and must not be * misrepresented as being the original software. Since few users * ever read sources, credits must appear in the documentation. * * 4. This notice may not be removed or altered. */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <ctype.h> #include <errno.h> #include "file.h" #ifndef lint static char *moduleid = "$OpenBSD: apprentice.c,v 1.3 1996/06/26 05:32:54 deraadt Exp $"; #endif /* lint */ #define EATAB {while (isascii((unsigned char) *l) && \ isspace((unsigned char) *l)) ++l;} #define LOWCASE(l) (isupper((unsigned char) (l)) ? \ tolower((unsigned char) (l)) : (l)) static int getvalue __P((struct magic *, char **)); static int hextoint __P((int)); static char *getstr __P((char *, char *, int, int *)); static int parse __P((char *, int *, int)); static void eatsize __P((char **)); static int maxmagic = 0; static int apprentice_1 __P((char *, int)); int apprentice(fn, check) char *fn; /* list of magic files */ int check; /* non-zero? checking-only run. */ { char *p, *mfn; int file_err, errs = -1; maxmagic = MAXMAGIS; magic = (struct magic *) calloc(sizeof(struct magic), maxmagic); mfn = malloc(strlen(fn)+1); if (magic == NULL || mfn == NULL) { (void) fprintf(stderr, "%s: Out of memory.\n", progname); if (check) return -1; else exit(1); } fn = strcpy(mfn, fn); while (fn) { p = strchr(fn, ':'); if (p) *p++ = '\0'; file_err = apprentice_1(fn, check); if (file_err > errs) errs = file_err; fn = p; } if (errs == -1) (void) fprintf(stderr, "%s: couldn't find any magic files!\n", progname); if (!check && errs) exit(1); free(mfn); return errs; } static int apprentice_1(fn, check) char *fn; /* name of magic file */ int check; /* non-zero? checking-only run. */ { static const char hdr[] = "cont\toffset\ttype\topcode\tmask\tvalue\tdesc"; FILE *f; char line[BUFSIZ+1]; int errs = 0; f = fopen(fn, "r"); if (f==NULL) { if (errno != ENOENT) (void) fprintf(stderr, "%s: can't read magic file %s (%s)\n", progname, fn, strerror(errno)); return -1; } /* parse it */ if (check) /* print silly verbose header for USG compat. */ (void) printf("%s\n", hdr); for (lineno = 1;fgets(line, BUFSIZ, f) != NULL; lineno++) { if (line[0]=='#') /* comment, do not parse */ continue; if (strlen(line) <= (unsigned)1) /* null line, garbage, etc */ continue; line[strlen(line)-1] = '\0'; /* delete newline */ if (parse(line, &nmagic, check) != 0) errs = 1; } (void) fclose(f); return errs; } /* * extend the sign bit if the comparison is to be signed */ unsigned long signextend(m, v) struct magic *m; unsigned long v; { if (!(m->flag & UNSIGNED)) switch(m->type) { /* * Do not remove the casts below. They are * vital. When later compared with the data, * the sign extension must have happened. */ case BYTE: v = (char) v; break; case SHORT: case BESHORT: case LESHORT: v = (short) v; break; case DATE: case BEDATE: case LEDATE: case LONG: case BELONG: case LELONG: v = (long) v; break; case STRING: break; default: magwarn("can't happen: m->type=%d\n", m->type); return -1; } return v; } /* * parse one line from magic file, put into magic[index++] if valid */ static int parse(l, ndx, check) char *l; int *ndx, check; { int i = 0, nd = *ndx; struct magic *m; char *t, *s; #define ALLOC_INCR 20 if (nd+1 >= maxmagic){ maxmagic += ALLOC_INCR; if ((magic = (struct magic *) realloc(magic, sizeof(struct magic) * maxmagic)) == NULL) { (void) fprintf(stderr, "%s: Out of memory.\n", progname); if (check) return -1; else exit(1); } memset(&magic[*ndx], 0, sizeof(struct magic) * ALLOC_INCR); } m = &magic[*ndx]; m->flag = 0; m->cont_level = 0; while (*l == '>') { ++l; /* step over */ m->cont_level++; } if (m->cont_level != 0 && *l == '(') { ++l; /* step over */ m->flag |= INDIR; } /* get offset, then skip over it */ m->offset = (int) strtoul(l,&t,0); if (l == t) magwarn("offset %s invalid", l); l = t; if (m->flag & INDIR) { m->in.type = LONG; m->in.offset = 0; /* * read [.lbs][+-]nnnnn) */ if (*l == '.') { l++; switch (LOWCASE(*l)) { case 'l': m->in.type = LONG; break; case 'h': case 's': m->in.type = SHORT; break; case 'c': case 'b': m->in.type = BYTE; break; default: magwarn("indirect offset type %c invalid", *l); break; } l++; } s = l; if (*l == '+' || *l == '-') l++; if (isdigit((unsigned char)*l)) { m->in.offset = strtoul(l, &t, 0); if (*s == '-') m->in.offset = - m->in.offset; } else t = l; if (*t++ != ')') magwarn("missing ')' in indirect offset"); l = t; } while (isascii((unsigned char)*l) && isdigit((unsigned char)*l)) ++l; EATAB; #define NBYTE 4 #define NSHORT 5 #define NLONG 4 #define NSTRING 6 #define NDATE 4 #define NBESHORT 7 #define NBELONG 6 #define NBEDATE 6 #define NLESHORT 7 #define NLELONG 6 #define NLEDATE 6 if (*l == 'u') { ++l; m->flag |= UNSIGNED; } /* get type, skip it */ if (strncmp(l, "byte", NBYTE)==0) { m->type = BYTE; l += NBYTE; } else if (strncmp(l, "short", NSHORT)==0) { m->type = SHORT; l += NSHORT; } else if (strncmp(l, "long", NLONG)==0) { m->type = LONG; l += NLONG; } else if (strncmp(l, "string", NSTRING)==0) { m->type = STRING; l += NSTRING; } else if (strncmp(l, "date", NDATE)==0) { m->type = DATE; l += NDATE; } else if (strncmp(l, "beshort", NBESHORT)==0) { m->type = BESHORT; l += NBESHORT; } else if (strncmp(l, "belong", NBELONG)==0) { m->type = BELONG; l += NBELONG; } else if (strncmp(l, "bedate", NBEDATE)==0) { m->type = BEDATE; l += NBEDATE; } else if (strncmp(l, "leshort", NLESHORT)==0) { m->type = LESHORT; l += NLESHORT; } else if (strncmp(l, "lelong", NLELONG)==0) { m->type = LELONG; l += NLELONG; } else if (strncmp(l, "ledate", NLEDATE)==0) { m->type = LEDATE; l += NLEDATE; } else { magwarn("type %s invalid", l); return -1; } /* New-style anding: "0 byte&0x80 =0x80 dynamically linked" */ if (*l == '&') { ++l; m->mask = signextend(m, strtoul(l, &l, 0)); eatsize(&l); } else m->mask = ~0L; EATAB; switch (*l) { case '>': case '<': /* Old-style anding: "0 byte &0x80 dynamically linked" */ case '&': case '^': case '=': m->reln = *l; ++l; break; case '!': if (m->type != STRING) { m->reln = *l; ++l; break; } /* FALL THROUGH */ default: if (*l == 'x' && isascii((unsigned char)l[1]) && isspace((unsigned char)l[1])) { m->reln = *l; ++l; goto GetDesc; /* Bill The Cat */ } m->reln = '='; break; } EATAB; if (getvalue(m, &l)) return -1; /* * TODO finish this macro and start using it! * #define offsetcheck {if (offset > HOWMANY-1) * magwarn("offset too big"); } */ /* * now get last part - the description */ GetDesc: EATAB; if (l[0] == '\b') { ++l; m->nospflag = 1; } else if ((l[0] == '\\') && (l[1] == 'b')) { ++l; ++l; m->nospflag = 1; } else m->nospflag = 0; while ((m->desc[i++] = *l++) != '\0' && i<MAXDESC) /* NULLBODY */; if (check) { mdump(m); } ++(*ndx); /* make room for next */ return 0; } /* * Read a numeric value from a pointer, into the value union of a magic * pointer, according to the magic type. Update the string pointer to point * just after the number read. Return 0 for success, non-zero for failure. */ static int getvalue(m, p) struct magic *m; char **p; { int slen; if (m->type == STRING) { *p = getstr(*p, m->value.s, sizeof(m->value.s), &slen); m->vallen = slen; } else if (m->reln != 'x') { m->value.l = signextend(m, strtoul(*p, p, 0)); eatsize(p); } return 0; } /* * Convert a string containing C character escapes. Stop at an unescaped * space or tab. * Copy the converted version to "p", returning its length in *slen. * Return updated scan pointer as function result. */ static char * getstr(s, p, plen, slen) register char *s; register char *p; int plen, *slen; { char *origs = s, *origp = p; char *pmax = p + plen - 1; register int c; register int val; while ((c = *s++) != '\0') { if (isspace((unsigned char) c)) break; if (p >= pmax) { fprintf(stderr, "String too long: %s\n", origs); break; } if(c == '\\') { switch(c = *s++) { case '\0': goto out; default: *p++ = (char) c; break; case 'n': *p++ = '\n'; break; case 'r': *p++ = '\r'; break; case 'b': *p++ = '\b'; break; case 't': *p++ = '\t'; break; case 'f': *p++ = '\f'; break; case 'v': *p++ = '\v'; break; /* \ and up to 3 octal digits */ case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': val = c - '0'; c = *s++; /* try for 2 */ if(c >= '0' && c <= '7') { val = (val<<3) | (c - '0'); c = *s++; /* try for 3 */ if(c >= '0' && c <= '7') val = (val<<3) | (c-'0'); else --s; } else --s; *p++ = (char)val; break; /* \x and up to 3 hex digits */ case 'x': val = 'x'; /* Default if no digits */ c = hextoint(*s++); /* Get next char */ if (c >= 0) { val = c; c = hextoint(*s++); if (c >= 0) { val = (val << 4) + c; c = hextoint(*s++); if (c >= 0) { val = (val << 4) + c; } else --s; } else --s; } else --s; *p++ = (char)val; break; } } else *p++ = (char)c; } out: *p = '\0'; *slen = p - origp; return s; } /* Single hex char to int; -1 if not a hex char. */ static int hextoint(c) int c; { if (!isascii((unsigned char) c)) return -1; if (isdigit((unsigned char) c)) return c - '0'; if ((c>='a')&&(c<='f')) return c + 10 - 'a'; if ((c>='A')&&(c<='F')) return c + 10 - 'A'; return -1; } /* * Print a string containing C character escapes. */ void showstr(fp, s, len) FILE *fp; const char *s; int len; { register char c; for (;;) { c = *s++; if (len == -1) { if (c == '\0') break; } else { if (len-- == 0) break; } if(c >= 040 && c <= 0176) /* TODO isprint && !iscntrl */ (void) fputc(c, fp); else { (void) fputc('\\', fp); switch (c) { case '\n': (void) fputc('n', fp); break; case '\r': (void) fputc('r', fp); break; case '\b': (void) fputc('b', fp); break; case '\t': (void) fputc('t', fp); break; case '\f': (void) fputc('f', fp); break; case '\v': (void) fputc('v', fp); break; default: (void) fprintf(fp, "%.3o", c & 0377); break; } } } } /* * eatsize(): Eat the size spec from a number [eg. 10UL] */ static void eatsize(p) char **p; { char *l = *p; if (LOWCASE(*l) == 'u') l++; switch (LOWCASE(*l)) { case 'l': /* long */ case 's': /* short */ case 'h': /* short */ case 'b': /* char/byte */ case 'c': /* char/byte */ l++; /*FALLTHROUGH*/ default: break; } *p = l; }