/* libpgm1.c - pgm utility library part 1 ** ** Copyright (C) 1989 by Jef Poskanzer. ** ** Permission to use, copy, modify, and distribute this software and its ** documentation for any purpose and without fee is hereby granted, provided ** that the above copyright notice appear in all copies and that both that ** copyright notice and this permission notice appear in supporting ** documentation. This software is provided "as is" without express or ** implied warranty. */ /* See pmfileio.c for the complicated explanation of this 32/64 bit file offset stuff. */ #define _FILE_OFFSET_BITS 64 #define _LARGE_FILES #include #include #include #include "netpbm/mallocvar.h" #include "netpbm/nstring.h" #include "pgm.h" #include "libpgm.h" #include "pbm.h" #include "libpbm.h" #include "pam.h" #include "libpam.h" #include "fileio.h" gray * pgm_allocrow(unsigned int const cols) { gray * grayrow; MALLOCARRAY(grayrow, cols); if (grayrow == NULL) pm_error("Unable to allocate space for a %u-column gray row", cols); return grayrow; } void pgm_init(int * const argcP, char ** const argv) { pbm_init(argcP, argv); } void pgm_nextimage(FILE * const file, int * const eofP) { pm_nextimage(file, eofP); } void pgm_readpgminitrest(FILE * const ifP, int * const colsP, int * const rowsP, gray * const maxvalP) { gray maxval; /* Read size. */ pbm_readpbminitrest(ifP, colsP, rowsP); /* Read maxval. */ maxval = pm_getuint(ifP); if (maxval > PGM_OVERALLMAXVAL) pm_error("maxval of input image (%u) is too large. " "The maximum allowed by the format is %u.", maxval, PGM_OVERALLMAXVAL); if (maxval == 0) pm_error("maxval of input image is zero."); *maxvalP = maxval; } void pgm_validateComputableSize(unsigned int const cols, unsigned int const rows) { /*---------------------------------------------------------------------------- Validate that the dimensions of the image are such that it can be processed in typical ways on this machine without worrying about overflows. Note that in C, arithmetic is always modulus arithmetic, so if your values are too big, the result is not what you expect. That failed expectation can be disastrous if you use it to allocate memory. It is very normal to allocate space for a pixel row, so we make sure the size of a pixel row, in bytes, can be represented by an 'int'. A common operation is adding 1 or 2 to the highest row or column number in the image, so we make sure that's possible. -----------------------------------------------------------------------------*/ if (cols > INT_MAX / (sizeof(gray)) || cols > INT_MAX - 2) pm_error("image width (%u) too large to be processed", cols); if (rows > INT_MAX - 2) pm_error("image height (%u) too large to be processed", rows); } void pgm_validateComputableMaxval(gray const maxval) { /*---------------------------------------------------------------------------- This is similar to validateComputableSize, but for the maxval. -----------------------------------------------------------------------------*/ /* Code sometimes allocates an array indexed by sample values and represents the size of that array as an INT. (UNSIGNED INT would be more proper, but there's no need to be that permissive). Code also sometimes iterates through sample values and quits when the value is greater than the maxval. Code often divides by the maxval, but we don't have to check for maxval == 0 as a computability problem because that is not a valid maxval. Note that in the PNM Plain formats, there is no upper limit for a maxval, though the 'gray' type does constrain what has been passed to us. */ if (maxval > INT_MAX-1) pm_error("Maxval (%u) is too large to be processed", maxval); } void pgm_readpgminit(FILE * const fileP, int * const colsP, int * const rowsP, gray * const maxvalP, int * const formatP) { int realFormat; /* Check magic number. */ realFormat = pm_readmagicnumber(fileP); switch (PAM_FORMAT_TYPE(realFormat)) { case PBM_TYPE: *formatP = realFormat; pbm_readpbminitrest(fileP, colsP, rowsP); /* Mathematically, it makes the most sense for the maxval of a PBM file seen as a PGM to be 1. But we tried this for a while and found that it causes unexpected results and frequent need for a Pnmdepth stage to convert the maxval to 255. You see, when you transform a PGM file in a way that causes interpolated gray shades, there's no in-between value to use when maxval is 1. It's really hard even to discover that your lack of Pnmdepth is your problem. So we pick 255, which is the most common PGM maxval, and the highest resolution you can get without increasing the size of the PGM image. So this means some programs that are capable of exploiting the bi-level nature of a PBM file must be PNM programs instead of PGM programs. */ *maxvalP = PGM_MAXMAXVAL; break; case PGM_TYPE: *formatP = realFormat; pgm_readpgminitrest(fileP, colsP, rowsP, maxvalP); break; case PPM_TYPE: pm_error("Input file is a PPM, which this program cannot process. " "You may want to convert it to PGM with 'ppmtopgm'"); case PAM_TYPE: pnm_readpaminitrestaspnm(fileP, colsP, rowsP, maxvalP, formatP); if (PAM_FORMAT_TYPE(*formatP) != PGM_TYPE) pm_error("Format of PAM input is not consistent with PGM"); break; default: pm_error("bad magic number 0x%x - not a PPM, PGM, PBM, or PAM file", realFormat); } pgm_validateComputableSize(*colsP, *rowsP); pgm_validateComputableMaxval(*maxvalP); } static void validateRpgmRow(gray * const grayrow, unsigned int const cols, gray const maxval, const char ** const errorP) { /*---------------------------------------------------------------------------- Check for sample values above maxval in input. Note: a program that wants to deal with invalid sample values itself can simply make sure it uses a sufficiently high maxval on the read function call, so this validation never fails. -----------------------------------------------------------------------------*/ if (maxval == 255 || maxval == 65535) { /* There's no way a sample can be invalid, so we don't need to look at the samples individually. */ *errorP = NULL; } else { unsigned int col; for (col = 0; col < cols; ++col) { if (grayrow[col] > maxval) { pm_asprintf(errorP, "gray value %u is greater than maxval (%u)", grayrow[col], maxval); return; } } *errorP = NULL; } } static void readRpgmRow(FILE * const fileP, gray * const grayrow, int const cols, gray const maxval, int const format) { unsigned int const bytesPerSample = maxval < 256 ? 1 : 2; int const bytesPerRow = cols * bytesPerSample; unsigned char * rowBuffer; const char * error; MALLOCARRAY(rowBuffer, bytesPerRow); if (rowBuffer == NULL) pm_asprintf(&error, "Unable to allocate memory for row buffer " "for %u columns", cols); else { size_t rc; rc = fread(rowBuffer, 1, bytesPerRow, fileP); if (rc == 0) pm_asprintf(&error, "Error reading row. fread() errno=%d (%s)", errno, strerror(errno)); else if (rc != bytesPerRow) pm_asprintf(&error, "Error reading row. Short read of %u bytes " "instead of %u", (unsigned)rc, bytesPerRow); else { if (maxval < 256) { unsigned int col; for (col = 0; col < cols; ++col) grayrow[col] = (gray)rowBuffer[col]; } else { unsigned int bufferCursor; unsigned int col; bufferCursor = 0; /* Start at beginning of rowBuffer[] */ for (col = 0; col < cols; ++col) { gray g; g = rowBuffer[bufferCursor++] << 8; g |= rowBuffer[bufferCursor++]; grayrow[col] = g; } } validateRpgmRow(grayrow, cols, maxval, &error); } free(rowBuffer); } if (error) { pm_errormsg("%s", error); pm_strfree(error); pm_longjmp(); } } static void readPbmRow(FILE * const fileP, gray * const grayrow, int const cols, gray const maxval, int const format) { jmp_buf jmpbuf; jmp_buf * origJmpbufP; bit * bitrow; bitrow = pbm_allocrow_packed(cols); if (setjmp(jmpbuf) != 0) { pbm_freerow(bitrow); pm_setjmpbuf(origJmpbufP); pm_longjmp(); } else { unsigned int col; pm_setjmpbufsave(&jmpbuf, &origJmpbufP); pbm_readpbmrow_packed(fileP, bitrow, cols, format); for (col = 0; col < cols; ++col) { grayrow[col] = ((bitrow[col/8] >> (7 - col%8)) & 0x1) == PBM_WHITE ? maxval : 0 ; } pm_setjmpbuf(origJmpbufP); } pbm_freerow(bitrow); } void pgm_readpgmrow(FILE * const fileP, gray * const grayrow, int const cols, gray const maxval, int const format) { switch (format) { case PGM_FORMAT: { unsigned int col; for (col = 0; col < cols; ++col) { grayrow[col] = pm_getuint(fileP); if (grayrow[col] > maxval) pm_error("value out of bounds (%u > %u)", grayrow[col], maxval); } } break; case RPGM_FORMAT: readRpgmRow(fileP, grayrow, cols, maxval, format); break; case PBM_FORMAT: case RPBM_FORMAT: readPbmRow(fileP, grayrow, cols, maxval, format); break; default: pm_error("can't happen"); } } gray ** pgm_readpgm(FILE * const fileP, int * const colsP, int * const rowsP, gray * const maxvalP) { gray ** grays; int rows, cols; gray maxval; int format; jmp_buf jmpbuf; jmp_buf * origJmpbufP; pgm_readpgminit(fileP, &cols, &rows, &maxval, &format); grays = pgm_allocarray(cols, rows); if (setjmp(jmpbuf) != 0) { pgm_freearray(grays, rows); pm_setjmpbuf(origJmpbufP); pm_longjmp(); } else { unsigned int row; pm_setjmpbufsave(&jmpbuf, &origJmpbufP); for (row = 0; row < rows; ++row) pgm_readpgmrow(fileP, grays[row], cols, maxval, format); pm_setjmpbuf(origJmpbufP); } *colsP = cols; *rowsP = rows; *maxvalP = maxval; return grays; } void pgm_check(FILE * const file, enum pm_check_type const checkType, int const format, int const cols, int const rows, gray const maxval, enum pm_check_code * const retvalP) { if (rows < 0) pm_error("Invalid number of rows passed to pgm_check(): %d", rows); if (cols < 0) pm_error("Invalid number of columns passed to pgm_check(): %d", cols); if (checkType != PM_CHECK_BASIC) { if (retvalP) *retvalP = PM_CHECK_UNKNOWN_TYPE; } else if (PGM_FORMAT_TYPE(format) == PBM_TYPE) { pbm_check(file, checkType, format, cols, rows, retvalP); } else if (format != RPGM_FORMAT) { if (retvalP) *retvalP = PM_CHECK_UNCHECKABLE; } else { pm_filepos const bytesPerRow = cols * (maxval > 255 ? 2 : 1); pm_filepos const needRasterSize = rows * bytesPerRow; pm_check(file, checkType, needRasterSize, retvalP); } }