1 | /* |
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2 | * $Id: stack.c,v 1.13 1999-01-22 23:09:06 ghudson Exp $ |
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3 | * |
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4 | * This program is part of a package including delete, undelete, |
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5 | * lsdel, expunge and purge. The software suite is meant as a |
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6 | * replacement for rm which allows for file recovery. |
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7 | * |
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8 | * Copyright (c) 1989 by the Massachusetts Institute of Technology. |
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9 | * For copying and distribution information, see the file "mit-copying.h." |
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10 | */ |
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11 | |
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12 | #if (!defined(lint) && !defined(SABER)) |
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13 | static char rcsid_stack_c[] = "$Id: stack.c,v 1.13 1999-01-22 23:09:06 ghudson Exp $"; |
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14 | #endif |
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15 | |
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16 | #include <string.h> |
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17 | #include <sys/types.h> |
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18 | #include <stdio.h> |
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19 | #include <errno.h> |
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20 | #include "stack.h" |
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21 | #include "delete_errs.h" |
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22 | #include "errors.h" |
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23 | #include "mit-copying.h" |
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24 | #include "util.h" |
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25 | |
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26 | #define STACK_INC 25 |
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27 | |
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28 | |
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29 | |
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30 | int dostack(data, op, bytes) |
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31 | caddr_t data; |
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32 | int op, bytes; |
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33 | { |
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34 | static caddr_t stack = (caddr_t) NULL; |
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35 | static int size = 0, count = 0; |
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36 | |
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37 | switch (op) { |
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38 | case EMPTY_STACK: |
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39 | if (size) { |
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40 | free(stack); |
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41 | stack = (caddr_t) NULL; |
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42 | size = count = 0; |
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43 | } |
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44 | #ifdef STACK_DEBUG |
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45 | fprintf(stderr, "dostack: return 1 (EMPTY_STACK).\n"); |
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46 | #endif |
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47 | return 0; |
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48 | case STACK_PUSH: |
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49 | if (bytes == 0) { |
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50 | #ifdef STACK_DEBUG |
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51 | fprintf(stderr, "Pushing 0 bytes at %d offset.\n", count); |
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52 | fprintf(stderr, "dostack: return 2 (STACK_PUSH).\n"); |
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53 | #endif |
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54 | return 0; |
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55 | } |
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56 | if (size - count < bytes) { |
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57 | do |
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58 | size += STACK_INC; |
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59 | while (size - count < bytes); |
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60 | stack = (caddr_t) (stack ? realloc((char *) stack, |
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61 | (unsigned) size) : |
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62 | Malloc((unsigned) size)); |
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63 | if ((! stack) && size) |
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64 | { |
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65 | size = count = 0; |
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66 | set_error(errno); |
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67 | error("Malloc"); |
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68 | #ifdef STACK_DEBUG |
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69 | fprintf(stderr, "dostack: return 3 (STACK_PUSH).\n"); |
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70 | #endif |
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71 | return error_code; |
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72 | } |
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73 | } |
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74 | #ifdef STACK_DEBUG |
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75 | fprintf(stderr, "Pushing %d bytes at %d offset.\n", bytes, count); |
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76 | #endif |
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77 | memcpy(stack + count, data, bytes); |
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78 | count += bytes; |
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79 | #ifdef STACK_DEBUG |
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80 | fprintf(stderr, "dostack: return 4 (STACK_PUSH).\n"); |
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81 | #endif |
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82 | return 0; |
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83 | case STACK_POP: |
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84 | if (bytes == 0) { |
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85 | #ifdef STACK_DEBUG |
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86 | fprintf(stderr, "Popping 0 bytes at %d offset.\n", count); |
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87 | fprintf(stderr, "dostack: return 5 (STACK_POP).\n"); |
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88 | #endif |
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89 | return 0; |
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90 | } |
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91 | if (count == 0) { |
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92 | set_status(STACK_EMPTY); |
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93 | #ifdef STACK_DEBUG |
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94 | fprintf(stderr, "dostack: return 6 (STACK_POP).\n"); |
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95 | #endif |
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96 | return error_code; |
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97 | } |
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98 | else { |
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99 | int newblocks, newsize; |
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100 | |
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101 | count -= bytes; |
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102 | #ifdef STACK_DEBUG |
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103 | fprintf(stderr, "Popping %d bytes at %d offset.\n", bytes, |
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104 | count); |
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105 | #endif |
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106 | memcpy(data, stack + count, bytes); |
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107 | newblocks = count / STACK_INC + ((count % STACK_INC) ? 1 : 0); |
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108 | newsize = newblocks * STACK_INC; |
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109 | if (newsize < size) { |
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110 | size = newsize; |
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111 | stack = (caddr_t) realloc((char *) stack, (unsigned) size); |
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112 | if ((! stack) && size) |
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113 | { |
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114 | set_error(errno); |
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115 | error("realloc"); |
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116 | #ifdef STACK_DEBUG |
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117 | fprintf(stderr, "dostack: return 7 (STACK_POP).\n"); |
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118 | #endif |
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119 | return error_code; |
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120 | } |
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121 | } |
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122 | #ifdef STACK_DEBUG |
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123 | fprintf(stderr, "dostack: return 8 (STACK_POP).\n"); |
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124 | #endif |
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125 | return 0; |
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126 | } |
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127 | default: |
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128 | set_error(STACK_BAD_OP); |
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129 | #ifdef STACK_DEBUG |
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130 | fprintf(stderr, "dostack: return 9.\n"); |
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131 | #endif |
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132 | return error_code; |
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133 | } |
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134 | } |
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