102 строки
3.1 KiB
C
102 строки
3.1 KiB
C
#include <stdio.h>
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#include <errno.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <string.h>
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int main() {
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char readBuffer[256] = {0};
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char writeBuffer[] = "writeme";
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int fl = open("/folder", O_RDWR);
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printf("read from folder: %d\n", read(fl, readBuffer, sizeof readBuffer));
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printf("errno: %d\n", errno);
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errno = 0;
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printf("write to folder: %d\n", write(fl, writeBuffer, sizeof writeBuffer));
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printf("errno: %d\n\n", errno);
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errno = 0;
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int bd = open("/broken-device", O_RDWR);
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printf("read from broken device: %d\n", read(bd, readBuffer, sizeof readBuffer));
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printf("errno: %d\n", errno);
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errno = 0;
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printf("write to broken device: %d\n", write(bd, writeBuffer, sizeof writeBuffer));
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printf("errno: %d\n\n", errno);
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errno = 0;
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int d = open("/device", O_RDWR);
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printf("read from device: %d\n", read(d, readBuffer, sizeof readBuffer));
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printf("data: %s\n", readBuffer);
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memset(readBuffer, 0, sizeof readBuffer);
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printf("errno: %d\n", errno);
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errno = 0;
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printf("write to device: %d\n", write(d, writeBuffer, sizeof writeBuffer));
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printf("errno: %d\n\n", errno);
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errno = 0;
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int f = open("/file", O_RDWR);
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printf("read from file: %d\n", read(f, readBuffer, sizeof readBuffer));
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printf("data: %s\n", readBuffer);
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memset(readBuffer, 0, sizeof readBuffer);
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printf("errno: %d\n\n", errno);
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errno = 0;
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printf("seek: %d\n", lseek(f, 3, SEEK_SET));
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printf("errno: %d\n\n", errno);
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printf("partial read from file: %d\n", read(f, readBuffer, 3));
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printf("data: %s\n", readBuffer);
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memset(readBuffer, 0, sizeof readBuffer);
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printf("errno: %d\n\n", errno);
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errno = 0;
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printf("seek: %d\n", lseek(f, -2, SEEK_END));
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printf("errno: %d\n", errno);
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errno = 0;
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printf("partial read from end of file: %d\n", read(f, readBuffer, 3));
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printf("data: %s\n", readBuffer);
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memset(readBuffer, 0, sizeof readBuffer);
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printf("errno: %d\n\n", errno);
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errno = 0;
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printf("seek: %d\n", lseek(f, -15, SEEK_CUR));
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printf("errno: %d\n", errno);
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errno = 0;
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printf("partial read from before start of file: %d\n", read(f, readBuffer, 3));
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printf("data: %s\n", readBuffer);
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memset(readBuffer, 0, sizeof readBuffer);
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printf("errno: %d\n\n", errno);
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errno = 0;
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printf("seek: %d\n", lseek(f, 0, SEEK_SET));
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printf("write to start of file: %d\n", write(f, writeBuffer, 3));
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printf("errno: %d\n\n", errno);
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errno = 0;
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printf("seek: %d\n", lseek(f, 0, SEEK_END));
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printf("write to end of file: %d\n", write(f, writeBuffer, 3));
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printf("errno: %d\n\n", errno);
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errno = 0;
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printf("seek: %d\n", lseek(f, 10, SEEK_END));
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printf("write after end of file: %d\n", write(f, writeBuffer, sizeof writeBuffer));
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printf("errno: %d\n\n", errno);
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errno = 0;
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int bytesRead;
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printf("seek: %d\n", lseek(f, 0, SEEK_SET));
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printf("read after write: %d\n", bytesRead = read(f, readBuffer, sizeof readBuffer));
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printf("errno: %d\n", errno);
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errno = 0;
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printf("final: ");
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for (int i = 0; i < bytesRead; i++) {
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if (readBuffer[i] == 0) {
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printf("\\0");
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} else {
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printf("%c", readBuffer[i]);
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}
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}
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printf("\n");
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return 0;
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}
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