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Diffstat (limited to 'src/is_simh.c')
| -rw-r--r-- | src/is_simh.c | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/src/is_simh.c b/src/is_simh.c new file mode 100644 index 0000000..4e78173 --- /dev/null +++ b/src/is_simh.c @@ -0,0 +1,209 @@ +/*- + * Copyright (c) 2023 Christos Zoulas + * All rights reserved. + * + * 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, 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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. + */ + +/* + * Parse SIM-H tape files + * http://simh.trailing-edge.com/docs/simh_magtape.pdf + */ + +#ifndef TEST +#include "file.h" + +#ifndef lint +FILE_RCSID("@(#)$File: is_simh.c,v 1.10 2023/07/27 19:39:55 christos Exp $") +#endif + +#include <string.h> +#include <stddef.h> +#include "magic.h" +#else +#include <stdint.h> +#include <sys/types.h> +#include <string.h> +#include <stddef.h> +#define CAST(a, b) (a)(b) +#endif + + +#ifdef DEBUG +#include <stdio.h> +#define DPRINTF(fmt, ...) printf(fmt, __VA_ARGS__) +#else +#define DPRINTF(fmt, ...) +#endif + +/* + * if SIMH_TAPEMARKS == 0: + * check all the records and tapemarks + * otherwise: + * check only up-to the number of tapemarks specified + */ +#ifndef SIMH_TAPEMARKS +#define SIMH_TAPEMARKS 10 +#endif + +typedef union { + char s[4]; + uint32_t u; +} myword; + +static myword simh_bo; + +#define NEED_SWAP (simh_bo.u == CAST(uint32_t, 0x01020304)) + +/* + * swap an int + */ +static uint32_t +swap4(uint32_t sv) +{ + myword d, s; + s.u = sv; + d.s[0] = s.s[3]; + d.s[1] = s.s[2]; + d.s[2] = s.s[1]; + d.s[3] = s.s[0]; + return d.u; +} + + +static uint32_t +getlen(const unsigned char **uc) +{ + uint32_t n; + memcpy(&n, *uc, sizeof(n)); + *uc += sizeof(n); + if (NEED_SWAP) + n = swap4(n); + if (n == 0xffffffff) /* check for End of Medium */ + return n; + n &= 0x00ffffff; /* keep only the record len */ + if (n & 1) + n++; + return n; +} + +static int +simh_parse(const unsigned char *uc, const unsigned char *ue) +{ + uint32_t nbytes, cbytes; + const unsigned char *orig_uc = uc; + size_t nt = 0, nr = 0; + + (void)memcpy(simh_bo.s, "\01\02\03\04", 4); + + while (ue - uc >= CAST(ptrdiff_t, sizeof(nbytes))) { + nbytes = getlen(&uc); + if ((nt > 0 || nr > 0) && nbytes == 0xFFFFFFFF) + /* EOM after at least one record or tapemark */ + break; + if (nbytes == 0) { + nt++; /* count tapemarks */ +#if SIMH_TAPEMARKS + if (nt == SIMH_TAPEMARKS) + break; +#endif + continue; + } + /* handle a data record */ + uc += nbytes; + if (ue - uc < CAST(ptrdiff_t, sizeof(nbytes))) + break; + cbytes = getlen(&uc); + if (nbytes != cbytes) + return 0; + nr++; + } + if (nt * sizeof(uint32_t) == CAST(size_t, uc - orig_uc)) + return 0; /* All examined data was tapemarks (0) */ + if (nr == 0) /* No records */ + return 0; + return 1; +} + +#ifndef TEST +int +file_is_simh(struct magic_set *ms, const struct buffer *b) +{ + const unsigned char *uc = CAST(const unsigned char *, b->fbuf); + const unsigned char *ue = uc + b->flen; + int mime = ms->flags & MAGIC_MIME; + + if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION)) != 0) + return 0; + + if (!simh_parse(uc, ue)) + return 0; + + if (mime == MAGIC_MIME_ENCODING) + return 1; + + if (mime) { + if (file_printf(ms, "application/SIMH-tape-data") == -1) + return -1; + return 1; + } + + if (file_printf(ms, "SIMH tape data") == -1) + return -1; + + return 1; +} + +#else + +#include <sys/types.h> +#include <sys/stat.h> +#include <stdio.h> +#include <fcntl.h> +#include <unistd.h> +#include <stdlib.h> +#include <stdint.h> +#include <err.h> + +int +main(int argc, char *argv[]) +{ + int fd; + struct stat st; + unsigned char *p; + + if ((fd = open(argv[1], O_RDONLY)) == -1) + err(EXIT_FAILURE, "Can't open `%s'", argv[1]); + + if (fstat(fd, &st) == -1) + err(EXIT_FAILURE, "Can't stat `%s'", argv[1]); + + if ((p = CAST(char *, malloc(st.st_size))) == NULL) + err(EXIT_FAILURE, "Can't allocate %jd bytes", + (intmax_t)st.st_size); + if (read(fd, p, st.st_size) != st.st_size) + err(EXIT_FAILURE, "Can't read %jd bytes", + (intmax_t)st.st_size); + printf("is simh %d\n", simh_parse(p, p + st.st_size)); + return 0; +} +#endif |