57 lines
1.8 KiB
C
57 lines
1.8 KiB
C
/*
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* Copyright (c) 2013, 2021 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* unistd/getlogin_r.c
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* Get name of user logged in at the controlling terminal.
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*/
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#include <errno.h>
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#include <pwd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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int getlogin_r(char* buf, size_t size)
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{
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struct passwd passwd_object;
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struct passwd* passwd;
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int errnum = 0;
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char* pwdbuf = NULL;
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size_t pwdbuflen = 0;
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do
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{
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// TODO: Potential overflow.
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size_t new_pwdbuflen = pwdbuflen ? 2 * pwdbuflen : 64;
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char* new_pwdbuf = (char*) realloc(pwdbuf, new_pwdbuflen);
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if ( !new_pwdbuf )
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return free(pwdbuf), -1;
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pwdbuf = new_pwdbuf;
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pwdbuflen = new_pwdbuflen;
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} while ( (errnum = getpwuid_r(getuid(), &passwd_object, pwdbuf, pwdbuflen,
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&passwd)) == ERANGE );
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if ( errnum )
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return free(pwdbuf), errno = errnum, -1;
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if ( !passwd )
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return free(pwdbuf), errno = ENOENT, -1;
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const char* username = passwd->pw_name;
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if ( size <= strlcpy(buf, username, size) )
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return free(pwdbuf), errno = ERANGE, -1;
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free(pwdbuf);
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return 0;
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}
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