121 lines
2.8 KiB
C
121 lines
2.8 KiB
C
/* cat.c -- provides a routine to output the contents of the named files in either a buffered or unbuffered fashion. */
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/* Accepts the following parameters: */
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/* -u: Output should be unbuffered. */
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/* Returns the following values: */
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/* 0: All files were printed successfully. */
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/* 1: One or more files could not be opened. */
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#include "common.h"
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/* If mode is set to zero, return a null pointer and print characters directly. Otherwise, return a pointer to a buffer containing */
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/* the contents of the file pointed to by fp. The size of the new buffer is stored in the int pointed to by bufsize. */
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char *cat(FILE *fp, const int mode, long unsigned *bufsize)
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{
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char c;
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if(!mode)
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{
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static long unsigned int i, finalbuflen, tmpbuflen;
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tmpbuflen = 4096;
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char *arr = malloc(tmpbuflen);
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char *tmparr = 0;
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char *finalarr = 0;
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for(i = 0, finalbuflen = 0; (c = fgetc(fp)) != EOF; i++, finalbuflen++)
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{
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if(i >= tmpbuflen)
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{
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tmpbuflen *= 2;
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tmparr = malloc(tmpbuflen);
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memcpy(tmparr, arr, tmpbuflen/2);
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free(arr);
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arr = tmparr;
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}
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arr[i] = c;
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}
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finalarr = malloc(finalbuflen);
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memcpy(finalarr, arr, finalbuflen);
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free(arr);
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arr = finalarr;
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*bufsize = finalbuflen;
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return arr;
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}
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else
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{
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for(;(c = fgetc(fp)) != EOF;)
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{
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putchar(c);
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}
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}
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return NULL;
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}
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int main(int argc, char **argv)
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{
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char *buf, *newbuf, *tmpbuf;
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long unsigned int i, upresence, fppresence;
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i = upresence = fppresence = 0;
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long unsigned int buflen, newbuflen;
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buflen = newbuflen = 0;
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FILE *fp;
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fp = 0;
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buf = newbuf = tmpbuf = 0;
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if((upresence = (getopt(argc, argv, ":u") == 'u')))
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{
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i++;
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}
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for(i++;argv[i] != NULL; i++)
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{
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if(!strcmp(argv[i], "-"))
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{
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fppresence++;
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newbuf = cat(fopen("/dev/stdin", "r"), upresence, &newbuflen);
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}
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else if((fp = fopen(argv[i], "r")) != NULL)
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{
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fppresence++;
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newbuf = cat(fp, upresence, &newbuflen);
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fclose(fp);
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}
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else
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{
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fprintf(stderr, "%s: failed to open %s. Aborting.\n", argv[0], argv[i]);
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exit(1);
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}
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/* This is where the actual magic happens. */
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if(!upresence)
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{
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/* Here, we copy buf and newbuf end-to-end into a new buffer of size buflen+newbuflen, then store that in buflen and */
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/* return a pointer to the new buffer. */
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tmpbuf = arrccat(buf, newbuf, &buflen, newbuflen);
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free(buf);
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buf = tmpbuf;
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}
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}
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if(!fppresence)
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{
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buf = cat(fopen("/dev/stdin", "r"), upresence, &buflen);
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}
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if(!upresence)
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{
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for(i = 0; i < buflen; i++)
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{
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putchar(buf[i]);
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}
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}
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exit(0);
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}
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