--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/libjpeg/cjpegalt.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,791 @@
+/*
+ * alternate cjpeg.c
+ *
+ * Copyright (C) 1991-1998, Thomas G. Lane.
+ * Modified 2009-2023 by Guido Vollbeding.
+ * This file is part of the Independent JPEG Group's software.
+ * For conditions of distribution and use, see the accompanying README file.
+ *
+ * This file contains an alternate user interface for the JPEG compressor.
+ * One or more input files are named on the command line, and output file
+ * names are created by substituting ".jpg" for the input file's extension.
+ */
+
+#include "cdjpeg.h"		/* Common decls for cjpeg/djpeg applications */
+#include "jversion.h"		/* for version message */
+
+#ifdef USE_CCOMMAND		/* command-line reader for Macintosh */
+#ifdef __MWERKS__
+#include <SIOUX.h>              /* Metrowerks needs this */
+#include <console.h>		/* ... and this */
+#endif
+#ifdef THINK_C
+#include <console.h>		/* Think declares it here */
+#endif
+#endif
+
+#ifndef PATH_MAX		/* ANSI maximum-pathname-length constant */
+#define PATH_MAX 256
+#endif
+
+
+/* Create the add-on message string table. */
+
+#define JMESSAGE(code,string)	string ,
+
+static const char * const cdjpeg_message_table[] = {
+#include "cderror.h"
+  NULL
+};
+
+
+/*
+ * Automatic determination of available memory.
+ */
+
+static long default_maxmem;	/* saves value determined at startup, or 0 */
+
+#ifndef FREE_MEM_ESTIMATE	/* may be defined from command line */
+
+#ifdef MSDOS			/* For MS-DOS (unless flat-memory model) */
+
+#include <dos.h>		/* for access to intdos() call */
+
+LOCAL(long)
+unused_dos_memory (void)
+/* Obtain total amount of unallocated DOS memory */
+{
+  union REGS regs;
+  long nparas;
+
+  regs.h.ah = 0x48;		/* DOS function Allocate Memory Block */
+  regs.x.bx = 0xFFFF;		/* Ask for more memory than DOS can have */
+  (void) intdos(&regs, &regs);
+  /* DOS will fail and return # of paragraphs actually available in BX. */
+  nparas = (unsigned int) regs.x.bx;
+  /* Times 16 to convert to bytes. */
+  return nparas << 4;
+}
+
+/* The default memory setting is 95% of the available space. */
+#define FREE_MEM_ESTIMATE  ((unused_dos_memory() * 95L) / 100L)
+
+#endif /* MSDOS */
+
+#ifdef ATARI	/* For Atari ST/Mega/STE/TT/Falcon, Pure C or Turbo C */
+
+#include <ext.h>
+
+/* The default memory setting is 90% of the available space. */
+#define FREE_MEM_ESTIMATE  (((long) coreleft() * 90L) / 100L)
+
+#endif /* ATARI */
+
+/* Add memory-estimation procedures for other operating systems here,
+ * with appropriate #ifdef's around them.
+ */
+
+#endif /* !FREE_MEM_ESTIMATE */
+
+
+/*
+ * This routine determines what format the input file is,
+ * and selects the appropriate input-reading module.
+ *
+ * To determine which family of input formats the file belongs to,
+ * we may look only at the first byte of the file, since C does not
+ * guarantee that more than one character can be pushed back with ungetc.
+ * Looking at additional bytes would require one of these approaches:
+ *     1) assume we can fseek() the input file (fails for piped input);
+ *     2) assume we can push back more than one character (works in
+ *        some C implementations, but unportable);
+ *     3) provide our own buffering (breaks input readers that want to use
+ *        stdio directly, such as the RLE library);
+ * or  4) don't put back the data, and modify the input_init methods to assume
+ *        they start reading after the start of file (also breaks RLE library).
+ * #1 is attractive for MS-DOS but is untenable on Unix.
+ *
+ * The most portable solution for file types that can't be identified by their
+ * first byte is to make the user tell us what they are.  This is also the
+ * only approach for "raw" file types that contain only arbitrary values.
+ * We presently apply this method for Targa files.  Most of the time Targa
+ * files start with 0x00, so we recognize that case.  Potentially, however,
+ * a Targa file could start with any byte value (byte 0 is the length of the
+ * seldom-used ID field), so we provide a switch to force Targa input mode.
+ */
+
+static boolean is_targa;	/* records user -targa switch */
+
+
+LOCAL(cjpeg_source_ptr)
+select_file_type (j_compress_ptr cinfo, FILE * infile)
+{
+  int c;
+
+  if (is_targa) {
+#ifdef TARGA_SUPPORTED
+    return jinit_read_targa(cinfo);
+#else
+    ERREXIT(cinfo, JERR_TGA_NOTCOMP);
+#endif
+  }
+
+  if ((c = getc(infile)) == EOF)
+    ERREXIT(cinfo, JERR_INPUT_EMPTY);
+  if (ungetc(c, infile) == EOF)
+    ERREXIT(cinfo, JERR_UNGETC_FAILED);
+
+  switch (c) {
+#ifdef BMP_SUPPORTED
+  case 'B':
+    return jinit_read_bmp(cinfo);
+#endif
+#ifdef GIF_SUPPORTED
+  case 'G':
+    return jinit_read_gif(cinfo);
+#endif
+#ifdef PPM_SUPPORTED
+  case 'P':
+    return jinit_read_ppm(cinfo);
+#endif
+#ifdef RLE_SUPPORTED
+  case 'R':
+    return jinit_read_rle(cinfo);
+#endif
+#ifdef TARGA_SUPPORTED
+  case 0x00:
+    return jinit_read_targa(cinfo);
+#endif
+  default:
+    ERREXIT(cinfo, JERR_UNKNOWN_FORMAT);
+    break;
+  }
+
+  return NULL;			/* suppress compiler warnings */
+}
+
+
+/*
+ * Argument-parsing code.
+ * The switch parser is designed to be useful with DOS-style command line
+ * syntax, ie, intermixed switches and file names, where only the switches
+ * to the left of a given file name affect processing of that file.
+ */
+
+
+static const char * progname;	/* program name for error messages */
+static char * outfilename;	/* for -outfile switch */
+
+
+LOCAL(void)
+usage (void)
+/* complain about bad command line */
+{
+  fprintf(stderr, "usage: %s [switches] inputfile(s)\n", progname);
+  fprintf(stderr, "List of input files may use wildcards (* and ?)\n");
+  fprintf(stderr, "Output filename is same as input filename, but extension .jpg\n");
+
+  fprintf(stderr, "Switches (names may be abbreviated):\n");
+  fprintf(stderr, "  -quality N[,...]   Compression quality (0..100; 5-95 is useful range)\n");
+  fprintf(stderr, "  -grayscale     Create monochrome JPEG file\n");
+  fprintf(stderr, "  -rgb           Create RGB JPEG file\n");
+#ifdef ENTROPY_OPT_SUPPORTED
+  fprintf(stderr, "  -optimize      Optimize Huffman table (smaller file, but slow compression)\n");
+#endif
+#ifdef C_PROGRESSIVE_SUPPORTED
+  fprintf(stderr, "  -progressive   Create progressive JPEG file\n");
+#endif
+#ifdef DCT_SCALING_SUPPORTED
+  fprintf(stderr, "  -scale M/N     Scale image by fraction M/N, eg, 1/2\n");
+#endif
+#ifdef TARGA_SUPPORTED
+  fprintf(stderr, "  -targa         Input file is Targa format (usually not needed)\n");
+#endif
+  fprintf(stderr, "Switches for advanced users:\n");
+#ifdef C_ARITH_CODING_SUPPORTED
+  fprintf(stderr, "  -arithmetic    Use arithmetic coding\n");
+#endif
+#ifdef DCT_SCALING_SUPPORTED
+  fprintf(stderr, "  -block N       DCT block size (1..16; default is 8)\n");
+#endif
+#if JPEG_LIB_VERSION_MAJOR >= 9
+  fprintf(stderr, "  -rgb1          Create RGB JPEG file with reversible color transform\n");
+  fprintf(stderr, "  -bgycc         Create big gamut YCC JPEG file\n");
+#endif
+#ifdef DCT_ISLOW_SUPPORTED
+  fprintf(stderr, "  -dct int       Use integer DCT method%s\n",
+	  (JDCT_DEFAULT == JDCT_ISLOW ? " (default)" : ""));
+#endif
+#ifdef DCT_IFAST_SUPPORTED
+  fprintf(stderr, "  -dct fast      Use fast integer DCT (less accurate)%s\n",
+	  (JDCT_DEFAULT == JDCT_IFAST ? " (default)" : ""));
+#endif
+#ifdef DCT_FLOAT_SUPPORTED
+  fprintf(stderr, "  -dct float     Use floating-point DCT method%s\n",
+	  (JDCT_DEFAULT == JDCT_FLOAT ? " (default)" : ""));
+#endif
+  fprintf(stderr, "  -nosmooth      Don't use high-quality downsampling\n");
+  fprintf(stderr, "  -restart N     Set restart interval in rows, or in blocks with B\n");
+#ifdef INPUT_SMOOTHING_SUPPORTED
+  fprintf(stderr, "  -smooth N      Smooth dithered input (N=1..100 is strength)\n");
+#endif
+#ifndef FREE_MEM_ESTIMATE
+  fprintf(stderr, "  -maxmemory N   Maximum memory to use (in kbytes)\n");
+#endif
+  fprintf(stderr, "  -outfile name  Specify name for output file\n");
+  fprintf(stderr, "  -verbose  or  -debug   Emit debug output\n");
+  fprintf(stderr, "Switches for wizards:\n");
+  fprintf(stderr, "  -baseline      Force baseline quantization tables\n");
+  fprintf(stderr, "  -qtables file  Use quantization tables given in file\n");
+  fprintf(stderr, "  -qslots N[,...]    Set component quantization tables\n");
+  fprintf(stderr, "  -sample HxV[,...]  Set component sampling factors\n");
+#ifdef C_MULTISCAN_FILES_SUPPORTED
+  fprintf(stderr, "  -scans file    Create multi-scan JPEG per script file\n");
+#endif
+  exit(EXIT_FAILURE);
+}
+
+
+LOCAL(int)
+parse_switches (j_compress_ptr cinfo, int argc, char **argv,
+		int last_file_arg_seen, boolean for_real)
+/* Parse optional switches.
+ * Returns argv[] index of first file-name argument (== argc if none).
+ * Any file names with indexes <= last_file_arg_seen are ignored;
+ * they have presumably been processed in a previous iteration.
+ * (Pass 0 for last_file_arg_seen on the first or only iteration.)
+ * for_real is FALSE on the first (dummy) pass; we may skip any expensive
+ * processing.
+ */
+{
+  int argn;
+  char * arg;
+  boolean force_baseline;
+  boolean simple_progressive;
+  char * qualityarg = NULL;	/* saves -quality parm if any */
+  char * qtablefile = NULL;	/* saves -qtables filename if any */
+  char * qslotsarg = NULL;	/* saves -qslots parm if any */
+  char * samplearg = NULL;	/* saves -sample parm if any */
+  char * scansarg = NULL;	/* saves -scans parm if any */
+
+  /* Set up default JPEG parameters. */
+
+  force_baseline = FALSE;	/* by default, allow 16-bit quantizers */
+  simple_progressive = FALSE;
+  is_targa = FALSE;
+  outfilename = NULL;
+  cinfo->err->trace_level = 0;
+  if (default_maxmem > 0)	/* override library's default value */
+    cinfo->mem->max_memory_to_use = default_maxmem;
+
+  /* Scan command line options, adjust parameters */
+
+  for (argn = 1; argn < argc; argn++) {
+    arg = argv[argn];
+    if (*arg != '-') {
+      /* Not a switch, must be a file name argument */
+      if (argn <= last_file_arg_seen) {
+	outfilename = NULL;	/* -outfile applies to just one input file */
+	continue;		/* ignore this name if previously processed */
+      }
+      break;			/* else done parsing switches */
+    }
+    arg++;			/* advance past switch marker character */
+
+    if (keymatch(arg, "arithmetic", 1)) {
+      /* Use arithmetic coding. */
+#ifdef C_ARITH_CODING_SUPPORTED
+      cinfo->arith_code = TRUE;
+#else
+      fprintf(stderr, "%s: sorry, arithmetic coding not supported\n",
+	      progname);
+      exit(EXIT_FAILURE);
+#endif
+
+    } else if (keymatch(arg, "baseline", 2)) {
+      /* Force baseline-compatible output (8-bit quantizer values). */
+      force_baseline = TRUE;
+
+    } else if (keymatch(arg, "block", 2)) {
+      /* Set DCT block size. */
+#if defined DCT_SCALING_SUPPORTED && JPEG_LIB_VERSION_MAJOR >= 8 && \
+      (JPEG_LIB_VERSION_MAJOR > 8 || JPEG_LIB_VERSION_MINOR >= 3)
+      int val;
+
+      if (++argn >= argc)	/* advance to next argument */
+	usage();
+      if (sscanf(argv[argn], "%d", &val) != 1)
+	usage();
+      if (val < 1 || val > 16)
+	usage();
+      cinfo->block_size = val;
+#else
+      fprintf(stderr, "%s: sorry, block size setting not supported\n",
+	      progname);
+      exit(EXIT_FAILURE);
+#endif
+
+    } else if (keymatch(arg, "dct", 2)) {
+      /* Select DCT algorithm. */
+      if (++argn >= argc)	/* advance to next argument */
+	usage();
+      if (keymatch(argv[argn], "int", 1)) {
+	cinfo->dct_method = JDCT_ISLOW;
+      } else if (keymatch(argv[argn], "fast", 2)) {
+	cinfo->dct_method = JDCT_IFAST;
+      } else if (keymatch(argv[argn], "float", 2)) {
+	cinfo->dct_method = JDCT_FLOAT;
+      } else
+	usage();
+
+    } else if (keymatch(arg, "debug", 1) || keymatch(arg, "verbose", 1)) {
+      /* Enable debug printouts. */
+      /* On first -d, print version identification */
+      static boolean printed_version = FALSE;
+
+      if (! printed_version) {
+	fprintf(stderr, "Independent JPEG Group's CJPEG, version %s\n%s\n",
+		JVERSION, JCOPYRIGHT);
+	printed_version = TRUE;
+      }
+      cinfo->err->trace_level++;
+
+    } else if (keymatch(arg, "grayscale", 2) || keymatch(arg, "greyscale",2)) {
+      /* Force a monochrome JPEG file to be generated. */
+      jpeg_set_colorspace(cinfo, JCS_GRAYSCALE);
+
+    } else if (keymatch(arg, "rgb", 3) || keymatch(arg, "rgb1", 4)) {
+      /* Force an RGB JPEG file to be generated. */
+#if JPEG_LIB_VERSION_MAJOR >= 9
+      /* Note: Entropy table assignment in jpeg_set_colorspace depends
+       * on color_transform.
+       */
+      cinfo->color_transform = arg[3] ? JCT_SUBTRACT_GREEN : JCT_NONE;
+#endif
+      jpeg_set_colorspace(cinfo, JCS_RGB);
+
+    } else if (keymatch(arg, "bgycc", 5)) {
+      /* Force a big gamut YCC JPEG file to be generated. */
+#if JPEG_LIB_VERSION_MAJOR >= 9 && \
+      (JPEG_LIB_VERSION_MAJOR > 9 || JPEG_LIB_VERSION_MINOR >= 1)
+      jpeg_set_colorspace(cinfo, JCS_BG_YCC);
+#else
+      fprintf(stderr, "%s: sorry, BG_YCC colorspace not supported\n",
+	      progname);
+      exit(EXIT_FAILURE);
+#endif
+
+    } else if (keymatch(arg, "maxmemory", 3)) {
+      /* Maximum memory in Kb (or Mb with 'm'). */
+      long lval;
+      char ch = 'x';
+
+      if (++argn >= argc)	/* advance to next argument */
+	usage();
+      if (sscanf(argv[argn], "%ld%c", &lval, &ch) < 1)
+	usage();
+      if (ch == 'm' || ch == 'M')
+	lval *= 1000L;
+      cinfo->mem->max_memory_to_use = lval * 1000L;
+
+    } else if (keymatch(arg, "nosmooth", 3)) {
+      /* Suppress fancy downsampling. */
+      cinfo->do_fancy_downsampling = FALSE;
+
+    } else if (keymatch(arg, "optimize", 1) || keymatch(arg, "optimise", 1)) {
+      /* Enable entropy parm optimization. */
+#ifdef ENTROPY_OPT_SUPPORTED
+      cinfo->optimize_coding = TRUE;
+#else
+      fprintf(stderr, "%s: sorry, entropy optimization was not compiled\n",
+	      progname);
+      exit(EXIT_FAILURE);
+#endif
+
+    } else if (keymatch(arg, "outfile", 4)) {
+      /* Set output file name. */
+      if (++argn >= argc)	/* advance to next argument */
+	usage();
+      outfilename = argv[argn];	/* save it away for later use */
+
+    } else if (keymatch(arg, "progressive", 1)) {
+      /* Select simple progressive mode. */
+#ifdef C_PROGRESSIVE_SUPPORTED
+      simple_progressive = TRUE;
+      /* We must postpone execution until num_components is known. */
+#else
+      fprintf(stderr, "%s: sorry, progressive output was not compiled\n",
+	      progname);
+      exit(EXIT_FAILURE);
+#endif
+
+    } else if (keymatch(arg, "quality", 1)) {
+      /* Quality ratings (quantization table scaling factors). */
+      if (++argn >= argc)	/* advance to next argument */
+	usage();
+      qualityarg = argv[argn];
+
+    } else if (keymatch(arg, "qslots", 2)) {
+      /* Quantization table slot numbers. */
+      if (++argn >= argc)	/* advance to next argument */
+	usage();
+      qslotsarg = argv[argn];
+      /* Must delay setting qslots until after we have processed any
+       * colorspace-determining switches, since jpeg_set_colorspace sets
+       * default quant table numbers.
+       */
+
+    } else if (keymatch(arg, "qtables", 2)) {
+      /* Quantization tables fetched from file. */
+      if (++argn >= argc)	/* advance to next argument */
+	usage();
+      qtablefile = argv[argn];
+      /* We postpone actually reading the file in case -quality comes later. */
+
+    } else if (keymatch(arg, "restart", 1)) {
+      /* Restart interval in MCU rows (or in MCUs with 'b'). */
+      long lval;
+      char ch = 'x';
+
+      if (++argn >= argc)	/* advance to next argument */
+	usage();
+      if (sscanf(argv[argn], "%ld%c", &lval, &ch) < 1)
+	usage();
+      if (lval < 0 || lval > 65535L)
+	usage();
+      if (ch == 'b' || ch == 'B') {
+	cinfo->restart_interval = (unsigned int) lval;
+	cinfo->restart_in_rows = 0; /* else prior '-restart n' overrides me */
+      } else {
+	cinfo->restart_in_rows = (int) lval;
+	/* restart_interval will be computed during startup */
+      }
+
+    } else if (keymatch(arg, "sample", 2)) {
+      /* Set sampling factors. */
+      if (++argn >= argc)	/* advance to next argument */
+	usage();
+      samplearg = argv[argn];
+      /* Must delay setting sample factors until after we have processed any
+       * colorspace-determining switches, since jpeg_set_colorspace sets
+       * default sampling factors.
+       */
+
+    } else if (keymatch(arg, "scale", 4)) {
+      /* Scale the image by a fraction M/N. */
+      if (++argn >= argc)	/* advance to next argument */
+	usage();
+      if (sscanf(argv[argn], "%d/%d",
+		 &cinfo->scale_num, &cinfo->scale_denom) != 2)
+	usage();
+
+    } else if (keymatch(arg, "scans", 4)) {
+      /* Set scan script. */
+#ifdef C_MULTISCAN_FILES_SUPPORTED
+      if (++argn >= argc)	/* advance to next argument */
+	usage();
+      scansarg = argv[argn];
+      /* We must postpone reading the file in case -progressive appears. */
+#else
+      fprintf(stderr, "%s: sorry, multi-scan output was not compiled\n",
+	      progname);
+      exit(EXIT_FAILURE);
+#endif
+
+    } else if (keymatch(arg, "smooth", 2)) {
+      /* Set input smoothing factor. */
+      int val;
+
+      if (++argn >= argc)	/* advance to next argument */
+	usage();
+      if (sscanf(argv[argn], "%d", &val) != 1)
+	usage();
+      if (val < 0 || val > 100)
+	usage();
+      cinfo->smoothing_factor = val;
+
+    } else if (keymatch(arg, "targa", 1)) {
+      /* Input file is Targa format. */
+      is_targa = TRUE;
+
+    } else {
+      usage();			/* bogus switch */
+    }
+  }
+
+  /* Post-switch-scanning cleanup */
+
+  if (for_real) {
+
+    /* Set quantization tables for selected quality. */
+    /* Some or all may be overridden if -qtables is present. */
+    if (qualityarg != NULL)	/* process -quality if it was present */
+      if (! set_quality_ratings(cinfo, qualityarg, force_baseline))
+	usage();
+
+    if (qtablefile != NULL)	/* process -qtables if it was present */
+      if (! read_quant_tables(cinfo, qtablefile, force_baseline))
+	usage();
+
+    if (qslotsarg != NULL)	/* process -qslots if it was present */
+      if (! set_quant_slots(cinfo, qslotsarg))
+	usage();
+
+    if (samplearg != NULL)	/* process -sample if it was present */
+      if (! set_sample_factors(cinfo, samplearg))
+	usage();
+
+#ifdef C_PROGRESSIVE_SUPPORTED
+    if (simple_progressive)	/* process -progressive; -scans can override */
+      jpeg_simple_progression(cinfo);
+#endif
+
+#ifdef C_MULTISCAN_FILES_SUPPORTED
+    if (scansarg != NULL)	/* process -scans if it was present */
+      if (! read_scan_script(cinfo, scansarg))
+	usage();
+#endif
+  }
+
+  return argn;			/* return index of next arg (file name) */
+}
+
+
+/*
+ * Check for overwrite of an existing file; clear it with user
+ */
+
+#ifndef NO_OVERWRITE_CHECK
+
+LOCAL(boolean)
+is_write_ok (char * outfname)
+{
+  FILE * ofile;
+  int ch;
+
+  ofile = fopen(outfname, READ_BINARY);
+  if (ofile == NULL)
+    return TRUE;		/* not present */
+  fclose(ofile);		/* oops, it is present */
+
+  for (;;) {
+    fprintf(stderr, "%s already exists, overwrite it? [y/n] ",
+	    outfname);
+    fflush(stderr);
+    ch = getc(stdin);
+    if (ch != '\n')		/* flush rest of line */
+      while (getc(stdin) != '\n')
+	/* nothing */;
+
+    switch (ch) {
+    case 'Y':
+    case 'y':
+      return TRUE;
+    case 'N':
+    case 'n':
+      return FALSE;
+    /* otherwise, ask again */
+    }
+  }
+}
+
+#endif
+
+
+/*
+ * Process a single input file name, and return its index in argv[].
+ * File names at or to left of old_file_index have been processed already.
+ */
+
+LOCAL(int)
+process_one_file (int argc, char **argv, int old_file_index)
+{
+  struct jpeg_compress_struct cinfo;
+  struct jpeg_error_mgr jerr;
+  char *infilename;
+  char workfilename[PATH_MAX];
+#ifdef PROGRESS_REPORT
+  struct cdjpeg_progress_mgr progress;
+#endif
+  int file_index;
+  cjpeg_source_ptr src_mgr;
+  FILE * input_file = NULL;
+  FILE * output_file = NULL;
+  JDIMENSION num_scanlines;
+
+  /* Initialize the JPEG compression object with default error handling. */
+  cinfo.err = jpeg_std_error(&jerr);
+  jpeg_create_compress(&cinfo);
+  /* Add some application-specific error messages (from cderror.h) */
+  jerr.addon_message_table = cdjpeg_message_table;
+  jerr.first_addon_message = JMSG_FIRSTADDONCODE;
+  jerr.last_addon_message = JMSG_LASTADDONCODE;
+
+  /* Now safe to enable signal catcher. */
+#ifdef NEED_SIGNAL_CATCHER
+  enable_signal_catcher((j_common_ptr) &cinfo);
+#endif
+
+  /* Initialize JPEG parameters.
+   * Much of this may be overridden later.
+   * In particular, we don't yet know the input file's color space,
+   * but we need to provide some value for jpeg_set_defaults() to work.
+   */
+
+  cinfo.in_color_space = JCS_RGB; /* arbitrary guess */
+  jpeg_set_defaults(&cinfo);
+
+  /* Scan command line to find next file name.
+   * It is convenient to use just one switch-parsing routine, but the switch
+   * values read here are ignored; we will rescan the switches after opening
+   * the input file.
+   */
+
+  file_index = parse_switches(&cinfo, argc, argv, old_file_index, FALSE);
+  if (file_index >= argc) {
+    fprintf(stderr, "%s: missing input file name\n", progname);
+    usage();
+  }
+
+  /* Open the input file. */
+  infilename = argv[file_index];
+  if ((input_file = fopen(infilename, READ_BINARY)) == NULL) {
+    fprintf(stderr, "%s: can't open %s\n", progname, infilename);
+    goto fail;
+  }
+
+#ifdef PROGRESS_REPORT
+  start_progress_monitor((j_common_ptr) &cinfo, &progress);
+#endif
+
+  /* Figure out the input file format, and set up to read it. */
+  src_mgr = select_file_type(&cinfo, input_file);
+  src_mgr->input_file = input_file;
+
+  /* Read the input file header to obtain file size & colorspace. */
+  (*src_mgr->start_input) (&cinfo, src_mgr);
+
+  /* Now that we know input colorspace, fix colorspace-dependent defaults */
+  jpeg_default_colorspace(&cinfo);
+
+  /* Adjust default compression parameters by re-parsing the options */
+  file_index = parse_switches(&cinfo, argc, argv, old_file_index, TRUE);
+
+  /* If user didn't supply -outfile switch, select output file name. */
+  if (outfilename == NULL) {
+    int i;
+
+    outfilename = workfilename;
+    /* Make outfilename be infilename with .jpg substituted for extension */
+    strcpy(outfilename, infilename);
+    for (i = (int)strlen(outfilename)-1; i >= 0; i--) {
+      switch (outfilename[i]) {
+      case ':':
+      case '/':
+      case '\\':
+	i = 0;			/* stop scanning */
+	break;
+      case '.':
+	outfilename[i] = '\0';	/* lop off existing extension */
+	i = 0;			/* stop scanning */
+	break;
+      default:
+	break;			/* keep scanning */
+      }
+    }
+    strcat(outfilename, ".jpg");
+  }
+
+  fprintf(stderr, "Compressing %s => %s\n", infilename, outfilename);
+#ifndef NO_OVERWRITE_CHECK
+  if (! is_write_ok(outfilename))
+    goto fail;
+#endif
+
+  /* Open the output file. */
+  if ((output_file = fopen(outfilename, WRITE_BINARY)) == NULL) {
+    fprintf(stderr, "%s: can't create %s\n", progname, outfilename);
+    goto fail;
+  }
+
+  /* Specify data destination for compression */
+  jpeg_stdio_dest(&cinfo, output_file);
+
+  /* Start compressor */
+  jpeg_start_compress(&cinfo, TRUE);
+
+  /* Process data */
+  while (cinfo.next_scanline < cinfo.image_height) {
+    num_scanlines = (*src_mgr->get_pixel_rows) (&cinfo, src_mgr);
+    (void) jpeg_write_scanlines(&cinfo, src_mgr->buffer, num_scanlines);
+  }
+
+  /* Finish compression and release memory */
+  (*src_mgr->finish_input) (&cinfo, src_mgr);
+  jpeg_finish_compress(&cinfo);
+
+  /* Clean up and exit */
+fail:
+  jpeg_destroy_compress(&cinfo);
+
+  if (input_file != NULL) fclose(input_file);
+  if (output_file != NULL) fclose(output_file);
+
+#ifdef PROGRESS_REPORT
+  end_progress_monitor((j_common_ptr) &cinfo);
+#endif
+
+  /* Disable signal catcher. */
+#ifdef NEED_SIGNAL_CATCHER
+  enable_signal_catcher((j_common_ptr) NULL);
+#endif
+
+  return file_index;
+}
+
+
+/*
+ * The main program.
+ */
+
+int
+main (int argc, char **argv)
+{
+  int file_index;
+
+  /* On Mac, fetch a command line. */
+#ifdef USE_CCOMMAND
+  argc = ccommand(&argv);
+#endif
+
+#ifdef MSDOS
+  progname = "cjpeg";		/* DOS tends to be too verbose about argv[0] */
+#else
+  progname = argv[0];
+  if (progname == NULL || progname[0] == 0)
+    progname = "cjpeg";		/* in case C library doesn't provide it */
+#endif
+
+  /* The default maxmem must be computed only once at program startup,
+   * since releasing memory with free() won't give it back to the OS.
+   */
+#ifdef FREE_MEM_ESTIMATE
+  default_maxmem = FREE_MEM_ESTIMATE;
+#else
+  default_maxmem = 0;
+#endif
+
+  /* Scan command line, parse switches and locate input file names */
+
+  if (argc < 2)
+    usage();			/* nothing on the command line?? */
+
+  file_index = 0;
+
+  while (file_index < argc-1)
+    file_index = process_one_file(argc, argv, file_index);
+
+  /* All done. */
+  exit(EXIT_SUCCESS);
+  return 0;			/* suppress no-return-value warnings */
+}