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+/*
+ * Copyright (c) 2000, 2001, 2002, 2003, 2004 by Martin C. Shepherd.
+ *
+ * All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, and/or sell copies of the Software, and to permit persons
+ * to whom the Software is furnished to do so, provided that the above
+ * copyright notice(s) and this permission notice appear in all copies of
+ * the Software and that both the above copyright notice(s) and this
+ * permission notice appear in supporting documentation.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+ * OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL
+ * INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING
+ * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+ * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
+ * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * Except as contained in this notice, the name of a copyright holder
+ * shall not be used in advertising or otherwise to promote the sale, use
+ * or other dealings in this Software without prior written authorization
+ * of the copyright holder.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+#include <errno.h>
+#include <locale.h>
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "libtecla.h"
+
+/*
+ * If the library is being built with file-system access excluded, this
+ * demo program won't have anything to demonstrate.
+ */
+#ifdef WITHOUT_FILE_SYSTEM
+int main(int argc, char *argv[])
+{
+ fprintf(stderr, "\n"
+ " This program normally demonstrates tecla's path-lookup\n"
+ " facility. However libtecla has been installed with\n"
+ " file-system facilities explicitly excluded, so there is\n"
+ " nothing to demonstrate.\n\n");
+ return 1;
+}
+#else
+/*
+ * Encapsulate the resources needed by this demo.
+ */
+typedef struct {
+ GetLine *gl; /* The line editor */
+ PathCache *pc; /* A cache of executables in the user's path */
+ PcaPathConf *ppc; /* The configuration argument of pca_path_completions() */
+} DemoRes;
+
+/*
+ * The following functions allocate and free instances of the above
+ * structure.
+ */
+static DemoRes *new_DemoRes(void);
+static DemoRes *del_DemoRes(DemoRes *res);
+
+/*
+ * Search backwards for the start of a pathname.
+ */
+static char *start_of_path(const char *string, int back_from);
+
+/*
+ * Find the array indexes of the first character of the first
+ * space-delimited word in the specified string, and of the character
+ * that follows it.
+ */
+static int get_word_limits(const char *string, int *wa, int *wb);
+
+/*
+ * This is the demonstration completion callback function (defined below).
+ */
+static CPL_MATCH_FN(demo_cpl_fn);
+
+/* The function which displays the introductory text of the demo */
+
+static void show_demo_introduction(GetLine *gl);
+
+/*.......................................................................
+ * This demo takes no arguments. It reads lines of input until the
+ * word 'exit' is entered, or C-d is pressed. It replaces the default
+ * tab-completion callback with one which when invoked at the start of
+ * a line, looks up completions of commands in the user's execution
+ * path, and when invoked in other parts of the line, reverts to
+ * normal filename completion. Whenever a new line is entered, it
+ * extracts the first word on the line, looks it up in the user's
+ * execution path to see if it corresponds to a known executable file,
+ * and if so, displays the full pathname of the file, along with the
+ * remaining arguments.
+ */
+int main(int argc, char *argv[])
+{
+ char *line; /* A line of input */
+ DemoRes *res; /* The resources of the demo */
+ int wa,wb; /* The delimiting indexes of a word in line[] */
+ int major,minor,micro; /* The version number of the library */
+/*
+ * Allocate the resources needed by this demo.
+ */
+ res = new_DemoRes();
+ if(!res)
+ return 1;
+/*
+ * If the user has the LC_CTYPE or LC_ALL environment variables set,
+ * enable display of characters corresponding to the specified locale.
+ */
+ (void) setlocale(LC_CTYPE, "");
+/*
+ * Lookup and display the version number of the library.
+ */
+ libtecla_version(&major, &minor, &micro);
+ printf("\n Welcome to the path-search demo of libtecla version %d.%d.%d\n",
+ major, minor, micro);
+/*
+ * Display some introductory text, left-justifying it within the current
+ * width of the terminal and enclosing it in a box of asterixes.
+ */
+ show_demo_introduction(res->gl);
+/*
+ * Read lines of input from the user and print them to stdout.
+ */
+ do {
+/*
+ * Get a new line from the user.
+ */
+ line = gl_get_line(res->gl, "$ ", NULL, 0);
+ if(!line)
+ break;
+/*
+ * Work out the extent of the first word in the input line, and
+ * try to identify this as a command in the path, displaying the
+ * full pathname of the match if found.
+ */
+ if(get_word_limits(line, &wa, &wb) == 0) {
+ char *cmd = pca_lookup_file(res->pc, line + wa, wb-wa, 0);
+ if(cmd) {
+ printf("Command=%s\n", cmd);
+ printf("Arguments=%s", line+wb);
+ } else {
+ printf("Command not found\n");
+ };
+ };
+/*
+ * If the user types "exit", quit the program.
+ */
+ if(strcmp(line, "exit\n")==0)
+ break;
+ } while(1);
+/*
+ * Clean up.
+ */
+ res = del_DemoRes(res);
+ return 0;
+}
+
+/*.......................................................................
+ * This completion callback searches for completions of executables in
+ * the user's path when invoked on a word at the start of the path, and
+ * performs normal filename completion elsewhere.
+ */
+static CPL_MATCH_FN(demo_cpl_fn)
+{
+/*
+ * Get the resource object that was passed to gl_customize_completion().
+ */
+ DemoRes *res = (DemoRes *) data;
+/*
+ * Find the start of the filename prefix to be completed, searching
+ * backwards for the first unescaped space, or the start of the line.
+ */
+ char *start = start_of_path(line, word_end);
+/*
+ * Skip spaces preceding the start of the prefix.
+ */
+ while(start > line && isspace((int)(unsigned char) start[-1]))
+ start--;
+/*
+ * If the filename prefix is at the start of the line, attempt
+ * to complete the filename as a command in the path. Otherwise
+ * perform normal filename completion.
+ */
+ return (start == line) ?
+ pca_path_completions(cpl, res->ppc, line, word_end) :
+ cpl_file_completions(cpl, NULL, line, word_end);
+}
+
+/*.......................................................................
+ * Search backwards for the potential start of a filename. This
+ * looks backwards from the specified index in a given string,
+ * stopping at the first unescaped space or the start of the line.
+ *
+ * Input:
+ * string const char * The string to search backwards in.
+ * back_from int The index of the first character in string[]
+ * that follows the pathname.
+ * Output:
+ * return char * The pointer to the first character of
+ * the potential pathname, or NULL on error.
+ */
+static char *start_of_path(const char *string, int back_from)
+{
+ int i, j;
+/*
+ * Search backwards from the specified index.
+ */
+ for(i=back_from-1; i>=0; i--) {
+ int c = string[i];
+/*
+ * Stop on unescaped spaces.
+ */
+ if(isspace((int)(unsigned char)c)) {
+/*
+ * The space can't be escaped if we are at the start of the line.
+ */
+ if(i==0)
+ break;
+/*
+ * Find the extent of the escape characters which precedes the space.
+ */
+ for(j=i-1; j>=0 && string[j]=='\\'; j--)
+ ;
+/*
+ * If there isn't an odd number of escape characters before the space,
+ * then the space isn't escaped.
+ */
+ if((i - 1 - j) % 2 == 0)
+ break;
+ };
+ };
+ return (char *)string + i + 1;
+}
+
+/*.......................................................................
+ * Create a new DemoRes object containing the resources needed by the
+ * demo.
+ *
+ * Output:
+ * return DemoRes * The new object, or NULL on error.
+ */
+static DemoRes *new_DemoRes(void)
+{
+ DemoRes *res; /* The object to be returned */
+/*
+ * Allocate the container.
+ */
+ res = (DemoRes *)malloc(sizeof(DemoRes));
+ if(!res) {
+ fprintf(stderr, "new_DemoRes: Insufficient memory.\n");
+ return NULL;
+ };
+/*
+ * Before attempting any operation that might fail, initialize the
+ * container at least up to the point at which it can safely be passed
+ * to del_DemoRes().
+ */
+ res->gl = NULL;
+ res->pc = NULL;
+ res->ppc = NULL;
+/*
+ * Create the line editor, specifying a max line length of 500 bytes,
+ * and 10000 bytes to allocate to storage of historical input lines.
+ */
+ res->gl = new_GetLine(500, 10000);
+ if(!res->gl)
+ return del_DemoRes(res);
+/*
+ * Enable text attribute formatting directives in prompt strings.
+ */
+ gl_prompt_style(res->gl, GL_FORMAT_PROMPT);
+/*
+ * Allocate a cache of the executable files found in the user's path.
+ */
+ res->pc = new_PathCache();
+ if(!res->pc)
+ return del_DemoRes(res);
+/*
+ * Populate the cache with the contents of the user's path.
+ */
+ if(pca_scan_path(res->pc, getenv("PATH")))
+ return del_DemoRes(res);
+/*
+ * Arrange for susequent calls to pca_lookup_file() and pca_path_completions()
+ * to only report files that are executable by the user.
+ */
+ pca_set_check_fn(res->pc, cpl_check_exe, NULL);
+/*
+ * Allocate a configuration object for use with pca_path_completions().
+ */
+ res->ppc = new_PcaPathConf(res->pc);
+ if(!res->ppc)
+ return del_DemoRes(res);
+/*
+ * Replace the builtin filename completion callback with one which
+ * searches for completions of executables in the user's path when
+ * invoked on a word at the start of the path, and completes files
+ * elsewhere.
+ */
+ if(gl_customize_completion(res->gl, res, demo_cpl_fn))
+ return del_DemoRes(res);
+ return res;
+}
+
+/*.......................................................................
+ * Delete a DemoRes object.
+ *
+ * Input:
+ * res DemoRes * The object to be deleted.
+ * Output:
+ * return DemoRes * The deleted object (always NULL).
+ */
+static DemoRes *del_DemoRes(DemoRes *res)
+{
+ if(res) {
+ res->gl = del_GetLine(res->gl);
+ res->pc = del_PathCache(res->pc);
+ res->ppc = del_PcaPathConf(res->ppc);
+ free(res);
+ };
+ return NULL;
+}
+
+/*.......................................................................
+ * Return the limits of the word at the start of a given string, ignoring
+ * leading white-space, and interpretting the first unescaped space, tab or
+ * the end of the line, as the end of the word.
+ *
+ * Input:
+ * string const char * The string to tokenize.
+ * Input/Output:
+ * wa,wb int * The indexes of the first character of the word,
+ * and the character which follows the last
+ * character of the word, will be assigned to
+ * *wa and *wb, respectively.
+ * Output:
+ * return int 0 - A word was found.
+ * 1 - No word was found before the end of the
+ * string.
+ */
+static int get_word_limits(const char *string, int *wa, int *wb)
+{
+ int escaped = 0; /* True if the next character is escaped */
+/*
+ * Skip leading white-space.
+ */
+ for(*wa=0; isspace((int)(unsigned char)string[*wa]); (*wa)++)
+ ;
+/*
+ * Find the first unescaped space, stopping early if the end of the
+ * string is reached.
+ */
+ for(*wb = *wa; ; (*wb)++) {
+ int c = string[*wb];
+ if(c=='\\')
+ escaped = !escaped;
+ else if((!escaped && isspace((int)(unsigned char)c)) || c=='\0')
+ break;
+ };
+ return *wa == *wb;
+}
+
+/*.......................................................................
+ * Display introductory text to the user, formatted according to the
+ * current terminal width and enclosed in a box of asterixes.
+ *
+ * Input:
+ * gl GetLine * The resource object of gl_get_line().
+ */
+static void show_demo_introduction(GetLine *gl)
+{
+ int start; /* The column in which gl_display_text() left the cursor */
+ int i;
+/*
+ * Break the indtroductory text into an array of strings, so as to
+ * avoid overflowing any compiler string limits.
+ */
+ const char *doc[] = {
+ "This program demonstrates the use of the pca_lookup_file() function ",
+ "for finding executables in the UNIX PATH. It also demonstrates ",
+ "tab completion of the names of executables found in the path. For ",
+ "example, if you type:\n\n ta\n\nthen hit the tab key, you will be ",
+ "presented with a list of executables such as tar and tail whose names ",
+ "start with the string \"ta\". If you decide to add an \"r\" to select ",
+ "the tar command, then you type return, the full pathname of the tar ",
+ "program will be printed.\n\nThe file demo2.c contains the code ",
+ "of this program, and is fully commented to enable its use as ",
+ "a working example of how to use the facilities documented in the ",
+ "pca_lookup_file man page.\n"};
+/*
+ * Form the top line of the documentation box by filling the area of
+ * the line between a " *" prefix and a "* " suffix with asterixes.
+ */
+ printf("\n");
+ gl_display_text(gl, 0, " *", "* ", '*', 80, 0, "\n");
+/*
+ * Justify the documentation text within margins of asterixes.
+ */
+ for(start=0,i=0; i<sizeof(doc)/sizeof(doc[0]) && start >= 0; i++)
+ start = gl_display_text(gl, 0, " * ", " * ", ' ', 80, start,doc[i]);
+/*
+ * Draw the bottom line of the documentation box.
+ */
+ gl_display_text(gl, 0, " *", "* ", '*', 80, 0, "\n");
+ printf("\n");
+}
+
+#endif /* ifndef WITHOUT_FILE_SYSTEM */
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