/*** *getpath.c - extract a pathname from an environment variable * * Copyright (c) 1989-1991, Microsoft Corporation. All rights reserved. * *Purpose: * Extract pathnames from a string of semicolon delimited pathnames * (generally the value of an environment variable such as PATH). * *Revision History: * 08-25-89 GJF Module created (taken from SEARCHEN.C and revised) * 03-14-90 GJF Replaced near with _CALLTYPE1 and added #include * * 07-25-90 SBM Replaced by * 10-04-90 GJF New-style function declarator. * 04-26-91 SRW Removed level 3 warnings * 09-18-91 JCR Strip off leading semi-colons (bug fix) * 09-25-91 JCR Changed ifdef "OS2" to "_HPFS_" and defined it * *******************************************************************************/ #include #include #include /* support HPFS file system */ #define _HPFS_ 1 /*** *_getpath() - extract a pathname from a semicolon-delimited list of pathnames * *Purpose: * To extract the next pathname from a semicolon-delimited list of * pathnames (usually the value on an environment variable) and copy * it to a caller-specified buffer. No check is done to see if the path * is valid. The maximum number of characters copied to the buffer is * maxlen - 1 (and then a '\0' is appended). * #ifdef _HPFS_ * If we hit a quoted string, then allow any characters inside. * For example, to put a semi-colon in a path, the user could have * an environment variable that looks like: * * PATH=C:\BIN;"D:\CRT\TOOLS;B1";C:\BINP #endif * * NOTE: Semi-colons in sequence are skipped over; pointers to 0-length * pathnames are NOT returned (this includes leading semi-colons). * * NOTE: If this routine is made user-callable, the near attribute * must be replaced by _LOAD_DS and the prototype moved from INTERNAL.H * to STDLIB.H. The source files MISC\SEARCHEN.C and EXEC\SPAWNVPE.C * will need to be recompiled, but should not require any changes. * *Entry: * src - Pointer to a string of 0 or more path specificiations, * delimited by semicolons (';'), and terminated by a null * character * dst - Pointer to the buffer where the next path specification is to * be copied * maxlen - Maximum number of characters to be copied, counting the * terminating null character. Note that a value of 0 is treated * as UINT_MAX + 1. * *Exit: * If a pathname is successfully extracted and copied, a pointer to the * first character of next pathname is returned (intervening semicolons * are skipped over). If the pathname is too long, as much as possible * is copied to the user-specified buffer and NULL is returned. * * Note that the no check is made of the validity of the copied pathname. * *Exceptions: * *******************************************************************************/ char * _CALLTYPE1 _getpath ( register const char *src, register char *dst, unsigned maxlen ) { const char *save_src; /* * strip off leading semi colons */ while ( *src == ';' ) src++; /* * Save original src pointer */ save_src = src; /* * Decrement maxlen to allow for the terminating '\0' */ if ( --maxlen == 0 ) goto appendnull; /* * Get the next path in src string */ while (*src && (*src != ';')) { #ifdef _HPFS_ /* * Check for quote char */ if (*src != '"') { *dst++ = *src++; if ( --maxlen == 0 ) { save_src = src; /* ensure NULL return */ goto appendnull; } } else { /* * Found a quote. Copy all chars until we hit the * final quote or the end of the string. */ src++; /* skip over opening quote */ while (*src && (*src != '"')) { *dst++ = *src++; if ( --maxlen == 0 ) { save_src = src; /* ensure NULL return */ goto appendnull; } } if (*src) src++; /* skip over closing quote */ } #else *dst++ = *src++; if ( --maxlen == 0 ) { save_src = src; /* ensure NULL return */ goto appendnull; } #endif } /* * If we copied something and stopped because of a ';', * skip the ';' before returning */ while ( *src == ';' ) src++; /* * Store a terminating null */ appendnull: *dst = '\0'; return((save_src != src) ? (char *)src : NULL); }