58 lines
1.4 KiB
C
58 lines
1.4 KiB
C
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include "dbg.h"
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int main(int argc, char *argv[])
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{
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int fd;
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int rc;
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long lrc;
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char *out;
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char buffer[1024];
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fpos_t pos;
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FILE *instream;
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FILE *outstream;
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check(argc == 2, "You must provide a filename.");
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fd = open(argv[1], O_RDWR | O_CREAT);
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check(fd != -1, "Unable to open \"%s\" for reading and writing.", argv[1]);
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rc = fchmod(fd, 0644);
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check(rc != -1, "Failed to chmod \"%s\"", argv[1]);
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outstream = fdopen(fd, "w");
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check(outstream != NULL, "Unable to open an outstream.");
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rc = fgetpos(outstream, &pos);
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check(rc != -1, "Failed to get position of outstream.");
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rc = fprintf(outstream, "It was written.");
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check(rc > 0, "Failed to write to outstream.");
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rc = fflush(outstream);
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check(rc != EOF, "Failed to flush outstream.");
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rc = fsetpos(outstream, &pos);
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check(rc != -1, "Failed to set outstream back to old position.");
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instream = fdopen(fd, "r");
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check(instream != NULL, "Unable to open an instream.");
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rewind(instream);
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lrc = ftell(instream);
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check(lrc == 0, "Failed to rewind instream.");
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out = fgets(buffer, 1023, instream);
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check(buffer != NULL, "Failed to read from instream.");
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printf("Read this from instream: \"%s\"\n", buffer);
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return 0;
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error:
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return 1;
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}
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