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6417 | ashmew2 | 1 | /* |
2 | * jmemname.c |
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3 | * |
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4 | * Copyright (C) 1992-1997, Thomas G. Lane. |
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5 | * This file is part of the Independent JPEG Group's software. |
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6 | * For conditions of distribution and use, see the accompanying README file. |
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7 | * |
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8 | * This file provides a generic implementation of the system-dependent |
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9 | * portion of the JPEG memory manager. This implementation assumes that |
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10 | * you must explicitly construct a name for each temp file. |
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11 | * Also, the problem of determining the amount of memory available |
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12 | * is shoved onto the user. |
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13 | */ |
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14 | |||
15 | #define JPEG_INTERNALS |
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16 | #include "jinclude.h" |
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17 | #include "jpeglib.h" |
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18 | #include "jmemsys.h" /* import the system-dependent declarations */ |
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19 | |||
20 | #ifndef HAVE_STDLIB_H /* |
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21 | extern void * malloc JPP((size_t size)); |
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22 | extern void free JPP((void *ptr)); |
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23 | #endif |
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24 | |||
25 | #ifndef SEEK_SET /* pre-ANSI systems may not define this; */ |
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26 | #define SEEK_SET 0 /* if not, assume 0 is correct */ |
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27 | #endif |
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28 | |||
29 | #ifdef DONT_USE_B_MODE /* define mode parameters for fopen() */ |
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30 | #define READ_BINARY "r" |
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31 | #define RW_BINARY "w+" |
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32 | #else |
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33 | #ifdef VMS /* VMS is very nonstandard */ |
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34 | #define READ_BINARY "rb", "ctx=stm" |
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35 | #define RW_BINARY "w+b", "ctx=stm" |
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36 | #else /* standard ANSI-compliant case */ |
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37 | #define READ_BINARY "rb" |
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38 | #define RW_BINARY "w+b" |
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39 | #endif |
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40 | #endif |
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41 | |||
42 | |||
43 | /* |
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44 | * Selection of a file name for a temporary file. |
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45 | * This is system-dependent! |
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46 | * |
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47 | * The code as given is suitable for most Unix systems, and it is easily |
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48 | * modified for most non-Unix systems. Some notes: |
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49 | * 1. The temp file is created in the directory named by TEMP_DIRECTORY. |
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50 | * The default value is /usr/tmp, which is the conventional place for |
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51 | * creating large temp files on Unix. On other systems you'll probably |
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52 | * want to change the file location. You can do this by editing the |
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53 | * #define, or (preferred) by defining TEMP_DIRECTORY in jconfig.h. |
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54 | * |
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55 | * 2. If you need to change the file name as well as its location, |
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56 | * you can override the TEMP_FILE_NAME macro. (Note that this is |
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57 | * actually a printf format string; it must contain %s and %d.) |
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58 | * Few people should need to do this. |
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59 | * |
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60 | * 3. mktemp() is used to ensure that multiple processes running |
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61 | * simultaneously won't select the same file names. If your system |
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62 | * doesn't have mktemp(), define NO_MKTEMP to do it the hard way. |
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63 | * (If you don't have |
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64 | * |
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65 | * 4. You probably want to define NEED_SIGNAL_CATCHER so that cjpeg.c/djpeg.c |
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66 | * will cause the temp files to be removed if you stop the program early. |
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67 | */ |
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68 | |||
69 | #ifndef TEMP_DIRECTORY /* can override from jconfig.h or Makefile */ |
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70 | #define TEMP_DIRECTORY "/usr/tmp/" /* recommended setting for Unix */ |
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71 | #endif |
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72 | |||
73 | static int next_file_num; /* to distinguish among several temp files */ |
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74 | |||
75 | #ifdef NO_MKTEMP |
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76 | |||
77 | #ifndef TEMP_FILE_NAME /* can override from jconfig.h or Makefile */ |
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78 | #define TEMP_FILE_NAME "%sJPG%03d.TMP" |
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79 | #endif |
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80 | |||
81 | #ifndef NO_ERRNO_H |
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82 | #include |
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83 | #endif |
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84 | |||
85 | /* ANSI C specifies that errno is a macro, but on older systems it's more |
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86 | * likely to be a plain int variable. And not all versions of errno.h |
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87 | * bother to declare it, so we have to in order to be most portable. Thus: |
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88 | */ |
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89 | #ifndef errno |
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90 | extern int errno; |
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91 | #endif |
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92 | |||
93 | |||
94 | LOCAL(void) |
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95 | select_file_name (char * fname) |
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96 | { |
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97 | FILE * tfile; |
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98 | |||
99 | /* Keep generating file names till we find one that's not in use */ |
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100 | for (;;) { |
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101 | next_file_num++; /* advance counter */ |
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102 | sprintf(fname, TEMP_FILE_NAME, TEMP_DIRECTORY, next_file_num); |
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103 | if ((tfile = fopen(fname, READ_BINARY)) == NULL) { |
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104 | /* fopen could have failed for a reason other than the file not |
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105 | * being there; for example, file there but unreadable. |
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106 | * If |
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107 | */ |
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108 | #ifdef ENOENT |
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109 | if (errno != ENOENT) |
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110 | continue; |
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111 | #endif |
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112 | break; |
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113 | } |
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114 | fclose(tfile); /* oops, it's there; close tfile & try again */ |
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115 | } |
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116 | } |
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117 | |||
118 | #else /* ! NO_MKTEMP */ |
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119 | |||
120 | /* Note that mktemp() requires the initial filename to end in six X's */ |
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121 | #ifndef TEMP_FILE_NAME /* can override from jconfig.h or Makefile */ |
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122 | #define TEMP_FILE_NAME "%sJPG%dXXXXXX" |
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123 | #endif |
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124 | |||
125 | LOCAL(void) |
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126 | select_file_name (char * fname) |
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127 | { |
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128 | next_file_num++; /* advance counter */ |
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129 | sprintf(fname, TEMP_FILE_NAME, TEMP_DIRECTORY, next_file_num); |
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130 | mktemp(fname); /* make sure file name is unique */ |
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131 | /* mktemp replaces the trailing XXXXXX with a unique string of characters */ |
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132 | } |
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133 | |||
134 | #endif /* NO_MKTEMP */ |
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135 | |||
136 | |||
137 | /* |
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138 | * Memory allocation and freeing are controlled by the regular library |
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139 | * routines malloc() and free(). |
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140 | */ |
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141 | |||
142 | GLOBAL(void *) |
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143 | jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject) |
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144 | { |
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145 | return (void *) malloc(sizeofobject); |
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146 | } |
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147 | |||
148 | GLOBAL(void) |
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149 | jpeg_free_small (j_common_ptr cinfo, void * object, size_t sizeofobject) |
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150 | { |
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151 | free(object); |
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152 | } |
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153 | |||
154 | |||
155 | /* |
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156 | * "Large" objects are treated the same as "small" ones. |
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157 | * NB: although we include FAR keywords in the routine declarations, |
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158 | * this file won't actually work in 80x86 small/medium model; at least, |
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159 | * you probably won't be able to process useful-size images in only 64KB. |
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160 | */ |
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161 | |||
162 | GLOBAL(void FAR *) |
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163 | jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject) |
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164 | { |
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165 | return (void FAR *) malloc(sizeofobject); |
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166 | } |
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167 | |||
168 | GLOBAL(void) |
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169 | jpeg_free_large (j_common_ptr cinfo, void FAR * object, size_t sizeofobject) |
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170 | { |
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171 | free(object); |
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172 | } |
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173 | |||
174 | |||
175 | /* |
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176 | * This routine computes the total memory space available for allocation. |
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177 | * It's impossible to do this in a portable way; our current solution is |
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178 | * to make the user tell us (with a default value set at compile time). |
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179 | * If you can actually get the available space, it's a good idea to subtract |
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180 | * a slop factor of 5% or so. |
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181 | */ |
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182 | |||
183 | #ifndef DEFAULT_MAX_MEM /* so can override from makefile */ |
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184 | #define DEFAULT_MAX_MEM 1000000L /* default: one megabyte */ |
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185 | #endif |
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186 | |||
187 | GLOBAL(long) |
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188 | jpeg_mem_available (j_common_ptr cinfo, long min_bytes_needed, |
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189 | long max_bytes_needed, long already_allocated) |
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190 | { |
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191 | return cinfo->mem->max_memory_to_use - already_allocated; |
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192 | } |
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193 | |||
194 | |||
195 | /* |
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196 | * Backing store (temporary file) management. |
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197 | * Backing store objects are only used when the value returned by |
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198 | * jpeg_mem_available is less than the total space needed. You can dispense |
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199 | * with these routines if you have plenty of virtual memory; see jmemnobs.c. |
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200 | */ |
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201 | |||
202 | |||
203 | METHODDEF(void) |
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204 | read_backing_store (j_common_ptr cinfo, backing_store_ptr info, |
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205 | void FAR * buffer_address, |
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206 | long file_offset, long byte_count) |
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207 | { |
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208 | if (fseek(info->temp_file, file_offset, SEEK_SET)) |
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209 | ERREXIT(cinfo, JERR_TFILE_SEEK); |
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210 | if (JFREAD(info->temp_file, buffer_address, byte_count) |
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211 | != (size_t) byte_count) |
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212 | ERREXIT(cinfo, JERR_TFILE_READ); |
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213 | } |
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214 | |||
215 | |||
216 | METHODDEF(void) |
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217 | write_backing_store (j_common_ptr cinfo, backing_store_ptr info, |
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218 | void FAR * buffer_address, |
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219 | long file_offset, long byte_count) |
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220 | { |
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221 | if (fseek(info->temp_file, file_offset, SEEK_SET)) |
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222 | ERREXIT(cinfo, JERR_TFILE_SEEK); |
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223 | if (JFWRITE(info->temp_file, buffer_address, byte_count) |
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224 | != (size_t) byte_count) |
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225 | ERREXIT(cinfo, JERR_TFILE_WRITE); |
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226 | } |
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227 | |||
228 | |||
229 | METHODDEF(void) |
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230 | close_backing_store (j_common_ptr cinfo, backing_store_ptr info) |
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231 | { |
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232 | fclose(info->temp_file); /* close the file */ |
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233 | unlink(info->temp_name); /* delete the file */ |
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234 | /* If your system doesn't have unlink(), use remove() instead. |
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235 | * remove() is the ANSI-standard name for this function, but if |
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236 | * your system was ANSI you'd be using jmemansi.c, right? |
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237 | */ |
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238 | TRACEMSS(cinfo, 1, JTRC_TFILE_CLOSE, info->temp_name); |
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239 | } |
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240 | |||
241 | |||
242 | /* |
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243 | * Initial opening of a backing-store object. |
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244 | */ |
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245 | |||
246 | GLOBAL(void) |
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247 | jpeg_open_backing_store (j_common_ptr cinfo, backing_store_ptr info, |
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248 | long total_bytes_needed) |
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249 | { |
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250 | select_file_name(info->temp_name); |
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251 | if ((info->temp_file = fopen(info->temp_name, RW_BINARY)) == NULL) |
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252 | ERREXITS(cinfo, JERR_TFILE_CREATE, info->temp_name); |
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253 | info->read_backing_store = read_backing_store; |
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254 | info->write_backing_store = write_backing_store; |
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255 | info->close_backing_store = close_backing_store; |
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256 | TRACEMSS(cinfo, 1, JTRC_TFILE_OPEN, info->temp_name); |
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257 | } |
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258 | |||
259 | |||
260 | /* |
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261 | * These routines take care of any system-dependent initialization and |
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262 | * cleanup required. |
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263 | */ |
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264 | |||
265 | GLOBAL(long) |
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266 | jpeg_mem_init (j_common_ptr cinfo) |
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267 | { |
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268 | next_file_num = 0; /* initialize temp file name generator */ |
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269 | return DEFAULT_MAX_MEM; /* default for max_memory_to_use */ |
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270 | } |
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271 | |||
272 | GLOBAL(void) |
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273 | jpeg_mem_term (j_common_ptr cinfo) |
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274 | { |
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275 | /* no work */ |
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276 | } |