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1 /* File ggets.c - goodgets is a safe alternative to gets */
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2 /* By C.B. Falconer. Public domain 2002-06-22 */
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3 /* attribution appreciated. */
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4
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5 /* Revised 2002-06-26 New prototype.
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6 2002-06-27 Incomplete final lines
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7 2006-06-14 Simplified, using getc, not fgets
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8 2006-06-15 Fixed memory leak at EOF
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9 */
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10
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11 /* fggets and ggets [which is fggets(ln, stdin)] set *ln to
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12 a buffer filled with the next complete line from the text
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13 stream f. The storage has been allocated within fggets,
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14 and is normally reduced to be an exact fit. The trailing
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15 \n has been removed, so the resultant line is ready for
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16 dumping with puts. The buffer will be as large as is
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17 required to hold the complete line.
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18
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19 Note: this means a final file line without a \n terminator
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20 has an effective \n appended, as EOF occurs within the read.
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21
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22 If no error occurs fggets returns 0. If an EOF occurs on
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23 the input file, EOF is returned. For memory allocation
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24 errors some positive value is returned. In this case *ln
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25 may point to a partial line. For other errors memory is
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26 freed and *ln is set to NULL.
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27
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28 Freeing of assigned storage is the callers responsibility
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29 */
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30
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31 #include <stdio.h>
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32 #include <stdlib.h>
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33 #include "ggets.h"
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34
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35 #define INITSIZE 112 /* power of 2 minus 16, helps malloc */
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36 #define DELTASIZE (INITSIZE + 16)
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37
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38 enum {OK = 0, NOMEM};
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39
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40 int fggets(char* *ln, FILE *f)
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41 {
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42 int cursize, ch, ix;
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43 char *buffer, *temp;
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44
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45 *ln = NULL; /* default */
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46 if (NULL == (buffer = malloc(INITSIZE))) return NOMEM;
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47 cursize = INITSIZE;
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48
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49 ix = 0;
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50 while ((EOF != (ch = getc(f))) && ('\n' != ch)) {
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51 if (ix >= (cursize - 1)) { /* extend buffer */
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52 cursize += DELTASIZE;
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53 if (NULL == (temp = realloc(buffer, (size_t)cursize))) {
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54 /* ran out of memory, return partial line */
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55 buffer[ix] = '\0';
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56 *ln = buffer;
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57 return NOMEM;
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58 }
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59 buffer = temp;
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60 }
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61 buffer[ix++] = ch;
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62 }
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63 if ((EOF == ch) && (0 == ix)) {
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64 free(buffer);
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65 return EOF;
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66 }
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67
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68 buffer[ix] = '\0';
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69 if (NULL == (temp = realloc(buffer, (size_t)ix + 1))) {
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70 *ln = buffer; /* without reducing it */
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71 }
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72 else *ln = temp;
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73 return OK;
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74 } /* fggets */
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75 /* End of ggets.c */
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