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Full Discussion: Problem with lseek call.
Top Forums Programming Problem with lseek call. Post 302916914 by Sir_Tomasz on Friday 12th of September 2014 01:15:13 PM
Old 09-12-2014
Problem with lseek call.

The following code:
Code:
    int fd;

    if (fd = open("mem", O_RDONLY) == -1)
        return 1;

    if (lseek(fd, 0, SEEK_SET) == -1) {
        char *buf = malloc(512);
        buf = strerror(errno);
        printf("%s\n", buf);
        return 1;
    }

always returns with "illegal seek" error. "mem" is executable with correct permissions. Can someone point me
in the right direction? Smilie
 

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GETCWD(3)						   BSD Library Functions Manual 						 GETCWD(3)

NAME
getcwd, getwd -- get working directory pathname LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <unistd.h> char * getcwd(char *buf, size_t size); char * getwd(char *buf); DESCRIPTION
The getcwd() function copies the absolute pathname of the current working directory into the memory referenced by buf and returns a pointer to buf. The size argument is the size, in bytes, of the array referenced by buf. If buf is NULL, space is allocated as necessary to store the pathname. This space may later be free(3)'d. The function getwd() is a compatibility routine which calls getcwd() with its buf argument and a size of MAXPATHLEN (as defined in the include file <sys/param.h>). Obviously, buf should be at least MAXPATHLEN bytes in length. These routines have traditionally been used by programs to save the name of a working directory for the purpose of returning to it. A much faster and less error-prone method of accomplishing this is to open the current directory ('.') and use the fchdir(2) function to return. RETURN VALUES
Upon successful completion, a pointer to the pathname is returned. Otherwise a NULL pointer is returned and the global variable errno is set to indicate the error. In addition, getwd() copies the error message associated with errno into the memory referenced by buf. ERRORS
The getcwd() function will fail if: [EINVAL] The size argument is zero. [ENOENT] A component of the pathname no longer exists. [ENOMEM] Insufficient memory is available. [ERANGE] The size argument is greater than zero but smaller than the length of the pathname plus 1. The getcwd() function may fail if: [EACCES] Read or search permission was denied for a component of the pathname. This is only checked in limited cases, depending on implementation details. SEE ALSO
chdir(2), fchdir(2), malloc(3), strerror(3) STANDARDS
The getcwd() function conforms to ISO/IEC 9945-1:1990 (``POSIX.1''). The ability to specify a NULL pointer and have getcwd() allocate memory as necessary is an extension. HISTORY
The getwd() function appeared in 4.0BSD. BUGS
The getwd() function does not do sufficient error checking and is not able to return very long, but valid, paths. It is provided for compat- ibility. BSD
April 17, 2010 BSD
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