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  1. /*
  2.  * Copyright (c) 2005 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup genericconsole
  30.  * @{
  31.  */
  32.  
  33. /**
  34.  * @file    kconsole.c
  35.  * @brief   Kernel console.
  36.  *
  37.  * This file contains kernel thread managing the kernel console.
  38.  */
  39.  
  40. #include <console/kconsole.h>
  41. #include <console/console.h>
  42. #include <console/chardev.h>
  43. #include <console/cmd.h>
  44. #include <print.h>
  45. #include <panic.h>
  46. #include <arch/types.h>
  47. #include <adt/list.h>
  48. #include <arch.h>
  49. #include <macros.h>
  50. #include <debug.h>
  51. #include <func.h>
  52. #include <string.h>
  53. #include <macros.h>
  54. #include <sysinfo/sysinfo.h>
  55. #include <ddi/device.h>
  56.  
  57. #ifdef CONFIG_SYMTAB
  58. #include <symtab.h>
  59. #endif
  60.  
  61. /** Simple kernel console.
  62.  *
  63.  * The console is realized by kernel thread kconsole.
  64.  * It doesn't understand any useful command on its own,
  65.  * but makes it possible for other kernel subsystems to
  66.  * register their own commands.
  67.  */
  68.  
  69. /** Locking.
  70.  *
  71.  * There is a list of cmd_info_t structures. This list
  72.  * is protected by cmd_lock spinlock. Note that specially
  73.  * the link elements of cmd_info_t are protected by
  74.  * this lock.
  75.  *
  76.  * Each cmd_info_t also has its own lock, which protects
  77.  * all elements thereof except the link element.
  78.  *
  79.  * cmd_lock must be acquired before any cmd_info lock.
  80.  * When locking two cmd info structures, structure with
  81.  * lower address must be locked first.
  82.  */
  83.  
  84. SPINLOCK_INITIALIZE(cmd_lock);  /**< Lock protecting command list. */
  85. LIST_INITIALIZE(cmd_head);  /**< Command list. */
  86.  
  87. static cmd_info_t *parse_cmdline(char *cmdline, size_t len);
  88. static bool parse_argument(char *cmdline, size_t len, index_t *start,
  89.     index_t *end);
  90. static char history[KCONSOLE_HISTORY][MAX_CMDLINE] = {};
  91.  
  92. /*
  93.  * For now, we use 0 as INR.
  94.  * However, it is therefore desirable to have architecture specific
  95.  * definition of KCONSOLE_VIRT_INR in the future.
  96.  */
  97. #define KCONSOLE_VIRT_INR  0
  98.  
  99. bool kconsole_notify = false;
  100. irq_t kconsole_irq;
  101.  
  102.  
  103. /** Allways refuse IRQ ownership.
  104.  *
  105.  * This is not a real IRQ, so we always decline.
  106.  *
  107.  * @return Always returns IRQ_DECLINE.
  108.  *
  109.  */
  110. static irq_ownership_t kconsole_claim(irq_t *irq)
  111. {
  112.     return IRQ_DECLINE;
  113. }
  114.  
  115.  
  116. /** Initialize kconsole data structures
  117.  *
  118.  * This is the most basic initialization, almost no
  119.  * other kernel subsystem is ready yet.
  120.  *
  121.  */
  122. void kconsole_init(void)
  123. {
  124.     unsigned int i;
  125.  
  126.     cmd_init();
  127.     for (i = 0; i < KCONSOLE_HISTORY; i++)
  128.         history[i][0] = '\0';
  129. }
  130.  
  131.  
  132. /** Initialize kconsole notification mechanism
  133.  *
  134.  * Initialize the virtual IRQ notification mechanism.
  135.  *
  136.  */
  137. void kconsole_notify_init(void)
  138. {
  139.     devno_t devno = device_assign_devno();
  140.    
  141.     sysinfo_set_item_val("kconsole.present", NULL, true);
  142.     sysinfo_set_item_val("kconsole.devno", NULL, devno);
  143.     sysinfo_set_item_val("kconsole.inr", NULL, KCONSOLE_VIRT_INR);
  144.    
  145.     irq_initialize(&kconsole_irq);
  146.     kconsole_irq.devno = devno;
  147.     kconsole_irq.inr = KCONSOLE_VIRT_INR;
  148.     kconsole_irq.claim = kconsole_claim;
  149.     irq_register(&kconsole_irq);
  150.    
  151.     kconsole_notify = true;
  152. }
  153.  
  154.  
  155. /** Register kconsole command.
  156.  *
  157.  * @param cmd Structure describing the command.
  158.  *
  159.  * @return 0 on failure, 1 on success.
  160.  */
  161. int cmd_register(cmd_info_t *cmd)
  162. {
  163.     link_t *cur;
  164.    
  165.     spinlock_lock(&cmd_lock);
  166.    
  167.     /*
  168.      * Make sure the command is not already listed.
  169.      */
  170.     for (cur = cmd_head.next; cur != &cmd_head; cur = cur->next) {
  171.         cmd_info_t *hlp;
  172.        
  173.         hlp = list_get_instance(cur, cmd_info_t, link);
  174.  
  175.         if (hlp == cmd) {
  176.             /* The command is already there. */
  177.             spinlock_unlock(&cmd_lock);
  178.             return 0;
  179.         }
  180.  
  181.         /* Avoid deadlock. */
  182.         if (hlp < cmd) {
  183.             spinlock_lock(&hlp->lock);
  184.             spinlock_lock(&cmd->lock);
  185.         } else {
  186.             spinlock_lock(&cmd->lock);
  187.             spinlock_lock(&hlp->lock);
  188.         }
  189.         if ((strncmp(hlp->name, cmd->name, max(strlen(cmd->name),
  190.             strlen(hlp->name))) == 0)) {
  191.             /* The command is already there. */
  192.             spinlock_unlock(&hlp->lock);
  193.             spinlock_unlock(&cmd->lock);
  194.             spinlock_unlock(&cmd_lock);
  195.             return 0;
  196.         }
  197.        
  198.         spinlock_unlock(&hlp->lock);
  199.         spinlock_unlock(&cmd->lock);
  200.     }
  201.    
  202.     /*
  203.      * Now the command can be added.
  204.      */
  205.     list_append(&cmd->link, &cmd_head);
  206.    
  207.     spinlock_unlock(&cmd_lock);
  208.     return 1;
  209. }
  210.  
  211. /** Print count times a character */
  212. static void rdln_print_c(char ch, int count)
  213. {
  214.     int i;
  215.     for (i = 0; i < count; i++)
  216.         putchar(ch);
  217. }
  218.  
  219. /** Insert character to string */
  220. static void insert_char(char *str, char ch, int pos)
  221. {
  222.     int i;
  223.    
  224.     for (i = strlen(str); i > pos; i--)
  225.         str[i] = str[i - 1];
  226.     str[pos] = ch;
  227. }
  228.  
  229. /** Try to find a command beginning with prefix */
  230. static const char *cmdtab_search_one(const char *name,link_t **startpos)
  231. {
  232.     size_t namelen = strlen(name);
  233.     const char *curname;
  234.  
  235.     spinlock_lock(&cmd_lock);
  236.  
  237.     if (!*startpos)
  238.         *startpos = cmd_head.next;
  239.  
  240.     for (; *startpos != &cmd_head; *startpos = (*startpos)->next) {
  241.         cmd_info_t *hlp;
  242.         hlp = list_get_instance(*startpos, cmd_info_t, link);
  243.  
  244.         curname = hlp->name;
  245.         if (strlen(curname) < namelen)
  246.             continue;
  247.         if (strncmp(curname, name, namelen) == 0) {
  248.             spinlock_unlock(&cmd_lock);
  249.             return curname+namelen;
  250.         }
  251.     }
  252.     spinlock_unlock(&cmd_lock);
  253.     return NULL;
  254. }
  255.  
  256.  
  257. /** Command completion of the commands
  258.  *
  259.  * @param name - string to match, changed to hint on exit
  260.  * @return number of found matches
  261.  */
  262. static int cmdtab_compl(char *name)
  263. {
  264.     static char output[/*MAX_SYMBOL_NAME*/128 + 1];
  265.     link_t *startpos = NULL;
  266.     const char *foundtxt;
  267.     int found = 0;
  268.     int i;
  269.  
  270.     output[0] = '\0';
  271.     while ((foundtxt = cmdtab_search_one(name, &startpos))) {
  272.         startpos = startpos->next;
  273.         if (!found)
  274.             strncpy(output, foundtxt, strlen(foundtxt) + 1);
  275.         else {
  276.             for (i = 0; output[i] && foundtxt[i] &&
  277.                 output[i] == foundtxt[i]; i++)
  278.                 ;
  279.             output[i] = '\0';
  280.         }
  281.         found++;
  282.     }
  283.     if (!found)
  284.         return 0;
  285.  
  286.     if (found > 1 && !strlen(output)) {
  287.         printf("\n");
  288.         startpos = NULL;
  289.         while ((foundtxt = cmdtab_search_one(name, &startpos))) {
  290.             cmd_info_t *hlp;
  291.             hlp = list_get_instance(startpos, cmd_info_t, link);
  292.             printf("%s - %s\n", hlp->name, hlp->description);
  293.             startpos = startpos->next;
  294.         }
  295.     }
  296.     strncpy(name, output, 128/*MAX_SYMBOL_NAME*/);
  297.     return found;
  298. }
  299.  
  300. static char *clever_readline(const char *prompt, indev_t *input)
  301. {
  302.     static int histposition = 0;
  303.  
  304.     static char tmp[MAX_CMDLINE + 1];
  305.     int curlen = 0, position = 0;
  306.     char *current = history[histposition];
  307.     int i;
  308.     char mod; /* Command Modifier */
  309.     char c;
  310.  
  311.     printf("%s> ", prompt);
  312.     while (1) {
  313.         c = _getc(input);
  314.         if (c == '\n') {
  315.             putchar(c);
  316.             break;
  317.         }
  318.         if (c == '\b') { /* Backspace */
  319.             if (position == 0)
  320.                 continue;
  321.             for (i = position; i < curlen; i++)
  322.                 current[i - 1] = current[i];
  323.             curlen--;
  324.             position--;
  325.             putchar('\b');
  326.             for (i = position; i < curlen; i++)
  327.                 putchar(current[i]);
  328.             putchar(' ');
  329.             rdln_print_c('\b', curlen - position + 1);
  330.             continue;
  331.         }
  332.         if (c == '\t') { /* Tabulator */
  333.             int found;
  334.  
  335.             /* Move to the end of the word */
  336.             for (; position < curlen && current[position] != ' ';
  337.                 position++)
  338.                 putchar(current[position]);
  339.             /* Copy to tmp last word */
  340.             for (i = position - 1; i >= 0 && current[i] != ' '; i--)
  341.                 ;
  342.             /* If word begins with * or &, skip it */
  343.             if (tmp[0] == '*' || tmp[0] == '&')
  344.                 for (i = 1; tmp[i]; i++)
  345.                     tmp[i - 1] = tmp[i];
  346.             i++; /* I is at the start of the word */
  347.             strncpy(tmp, current + i, position - i + 1);
  348.  
  349.             if (i == 0) { /* Command completion */
  350.                 found = cmdtab_compl(tmp);
  351.             } else { /* Symtab completion */
  352. #ifdef CONFIG_SYMTAB
  353.                 found = symtab_compl(tmp);
  354. #else
  355.                 found = 0;
  356. #endif
  357.             }
  358.  
  359.             if (found == 0)
  360.                 continue;
  361.             for (i = 0; tmp[i] && curlen < MAX_CMDLINE;
  362.                 i++, curlen++)
  363.                 insert_char(current, tmp[i], i + position);
  364.  
  365.             if (strlen(tmp) || found == 1) { /* If we have a hint */
  366.                 for (i = position; i < curlen; i++)
  367.                     putchar(current[i]);
  368.                 position += strlen(tmp);
  369.                 /* Add space to end */
  370.                 if (found == 1 && position == curlen &&
  371.                     curlen < MAX_CMDLINE) {
  372.                     current[position] = ' ';
  373.                     curlen++;
  374.                     position++;
  375.                     putchar(' ');
  376.                 }
  377.             } else { /* No hint, table was printed */
  378.                 printf("%s> ", prompt);
  379.                 for (i = 0; i < curlen; i++)
  380.                     putchar(current[i]);
  381.                 position += strlen(tmp);
  382.             }
  383.             rdln_print_c('\b', curlen - position);
  384.             continue;
  385.         }
  386.         if (c == 0x1b) { /* Special command */
  387.             mod = _getc(input);
  388.             c = _getc(input);
  389.  
  390.             if (mod != 0x5b && mod != 0x4f)
  391.                 continue;
  392.  
  393.             if (c == 0x33 && _getc(input) == 0x7e) {
  394.                 /* Delete */
  395.                 if (position == curlen)
  396.                     continue;
  397.                 for (i = position + 1; i < curlen; i++) {
  398.                     putchar(current[i]);
  399.                     current[i - 1] = current[i];
  400.                 }
  401.                 putchar(' ');
  402.                 rdln_print_c('\b', curlen - position);
  403.                 curlen--;
  404.             } else if (c == 0x48) { /* Home */
  405.                 rdln_print_c('\b', position);
  406.                 position = 0;
  407.             } else if (c == 0x46) {  /* End */
  408.                 for (i = position; i < curlen; i++)
  409.                     putchar(current[i]);
  410.                 position = curlen;
  411.             } else if (c == 0x44) { /* Left */
  412.                 if (position > 0) {
  413.                     putchar('\b');
  414.                     position--;
  415.                 }
  416.                 continue;
  417.             } else if (c == 0x43) { /* Right */
  418.                 if (position < curlen) {
  419.                     putchar(current[position]);
  420.                     position++;
  421.                 }
  422.                 continue;
  423.             } else if (c == 0x41 || c == 0x42) {
  424.                                 /* Up, down */
  425.                 rdln_print_c('\b', position);
  426.                 rdln_print_c(' ', curlen);
  427.                 rdln_print_c('\b', curlen);
  428.                 if (c == 0x41) /* Up */
  429.                     histposition--;
  430.                 else
  431.                     histposition++;
  432.                 if (histposition < 0) {
  433.                     histposition = KCONSOLE_HISTORY - 1;
  434.                 } else {
  435.                     histposition =
  436.                         histposition % KCONSOLE_HISTORY;
  437.                 }
  438.                 current = history[histposition];
  439.                 printf("%s", current);
  440.                 curlen = strlen(current);
  441.                 position = curlen;
  442.                 continue;
  443.             }
  444.             continue;
  445.         }
  446.         if (curlen >= MAX_CMDLINE)
  447.             continue;
  448.  
  449.         insert_char(current, c, position);
  450.  
  451.         curlen++;
  452.         for (i = position; i < curlen; i++)
  453.             putchar(current[i]);
  454.         position++;
  455.         rdln_print_c('\b',curlen - position);
  456.     }
  457.     if (curlen) {
  458.         histposition++;
  459.         histposition = histposition % KCONSOLE_HISTORY;
  460.     }
  461.     current[curlen] = '\0';
  462.     return current;
  463. }
  464.  
  465. bool kconsole_check_poll(void)
  466. {
  467.     return check_poll(stdin);
  468. }
  469.  
  470. /** Kernel console prompt.
  471.  *
  472.  * @param prompt Kernel console prompt (e.g kconsole/panic).
  473.  * @param msg    Message to display in the beginning.
  474.  * @param kcon   Wait for keypress to show the prompt
  475.  *               and never exit.
  476.  *
  477.  */
  478. void kconsole(char *prompt, char *msg, bool kcon)
  479. {
  480.     cmd_info_t *cmd_info;
  481.     count_t len;
  482.     char *cmdline;
  483.    
  484.     if (!stdin) {
  485.         LOG("No stdin for kernel console");
  486.         return;
  487.     }
  488.    
  489.     if (msg)
  490.         printf("%s", msg);
  491.    
  492.     if (kcon)
  493.         _getc(stdin);
  494.     else
  495.         printf("Type \"exit\" to leave the console.\n");
  496.    
  497.     while (true) {
  498.         cmdline = clever_readline((char *) prompt, stdin);
  499.         len = strlen(cmdline);
  500.         if (!len)
  501.             continue;
  502.        
  503.         if ((!kcon) && (len == 4) && (strncmp(cmdline, "exit", 4) == 0))
  504.             break;
  505.        
  506.         cmd_info = parse_cmdline(cmdline, len);
  507.         if (!cmd_info)
  508.             continue;
  509.        
  510.         (void) cmd_info->func(cmd_info->argv);
  511.     }
  512. }
  513.  
  514. /** Kernel console managing thread.
  515.  *
  516.  */
  517. void kconsole_thread(void *data)
  518. {
  519.     kconsole("kconsole", "Kernel console ready (press any key to activate)\n", true);
  520. }
  521.  
  522. static int parse_int_arg(char *text, size_t len, unative_t *result)
  523. {
  524.     uintptr_t symaddr;
  525.     bool isaddr = false;
  526.     bool isptr = false;
  527.  
  528. #ifdef CONFIG_SYMTAB
  529.     static char symname[MAX_SYMBOL_NAME];
  530. #endif
  531.    
  532.     /* If we get a name, try to find it in symbol table */
  533.     if (text[0] == '&') {
  534.         isaddr = true;
  535.         text++;
  536.         len--;
  537.     } else if (text[0] == '*') {
  538.         isptr = true;
  539.         text++;
  540.         len--;
  541.     }
  542.     if (text[0] < '0' || text[0] > '9') {
  543. #ifdef CONFIG_SYMTAB
  544.         strncpy(symname, text, min(len + 1, MAX_SYMBOL_NAME));
  545.         symaddr = get_symbol_addr(symname);
  546.         if (!symaddr) {
  547.             printf("Symbol %s not found.\n", symname);
  548.             return -1;
  549.         }
  550.         if (symaddr == (uintptr_t) -1) {
  551.             printf("Duplicate symbol %s.\n", symname);
  552.             symtab_print_search(symname);
  553.             return -1;
  554.         }
  555. #else
  556.         symaddr = 0;
  557. #endif
  558.         if (isaddr)
  559.             *result = (unative_t)symaddr;
  560.         else if (isptr)
  561.             *result = **((unative_t **)symaddr);
  562.         else
  563.             *result = *((unative_t *)symaddr);
  564.     } else { /* It's a number - convert it */
  565.         *result = atoi(text);
  566.         if (isptr)
  567.             *result = *((unative_t *)*result);
  568.     }
  569.  
  570.     return 0;
  571. }
  572.  
  573. /** Parse command line.
  574.  *
  575.  * @param cmdline Command line as read from input device.
  576.  * @param len Command line length.
  577.  *
  578.  * @return Structure describing the command.
  579.  */
  580. cmd_info_t *parse_cmdline(char *cmdline, size_t len)
  581. {
  582.     index_t start = 0, end = 0;
  583.     cmd_info_t *cmd = NULL;
  584.     link_t *cur;
  585.     count_t i;
  586.     int error = 0;
  587.    
  588.     if (!parse_argument(cmdline, len, &start, &end)) {
  589.         /* Command line did not contain alphanumeric word. */
  590.         return NULL;
  591.     }
  592.  
  593.     spinlock_lock(&cmd_lock);
  594.    
  595.     for (cur = cmd_head.next; cur != &cmd_head; cur = cur->next) {
  596.         cmd_info_t *hlp;
  597.        
  598.         hlp = list_get_instance(cur, cmd_info_t, link);
  599.         spinlock_lock(&hlp->lock);
  600.        
  601.         if (strncmp(hlp->name, &cmdline[start], max(strlen(hlp->name),
  602.             end - start + 1)) == 0) {
  603.             cmd = hlp;
  604.             break;
  605.         }
  606.        
  607.         spinlock_unlock(&hlp->lock);
  608.     }
  609.    
  610.     spinlock_unlock(&cmd_lock);
  611.    
  612.     if (!cmd) {
  613.         /* Unknown command. */
  614.         printf("Unknown command.\n");
  615.         return NULL;
  616.     }
  617.  
  618.     /* cmd == hlp is locked */
  619.    
  620.     /*
  621.      * The command line must be further analyzed and
  622.      * the parameters therefrom must be matched and
  623.      * converted to those specified in the cmd info
  624.      * structure.
  625.      */
  626.  
  627.     for (i = 0; i < cmd->argc; i++) {
  628.         char *buf;
  629.         start = end + 1;
  630.         if (!parse_argument(cmdline, len, &start, &end)) {
  631.             printf("Too few arguments.\n");
  632.             spinlock_unlock(&cmd->lock);
  633.             return NULL;
  634.         }
  635.        
  636.         error = 0;
  637.         switch (cmd->argv[i].type) {
  638.         case ARG_TYPE_STRING:
  639.             buf = (char *) cmd->argv[i].buffer;
  640.             strncpy(buf, (const char *) &cmdline[start],
  641.                 min((end - start) + 2, cmd->argv[i].len));
  642.             buf[min((end - start) + 1, cmd->argv[i].len - 1)] =
  643.                 '\0';
  644.             break;
  645.         case ARG_TYPE_INT:
  646.             if (parse_int_arg(cmdline + start, end - start + 1,
  647.                 &cmd->argv[i].intval))
  648.                 error = 1;
  649.             break;
  650.         case ARG_TYPE_VAR:
  651.             if (start != end && cmdline[start] == '"' &&
  652.                 cmdline[end] == '"') {
  653.                 buf = (char *) cmd->argv[i].buffer;
  654.                 strncpy(buf, (const char *) &cmdline[start + 1],
  655.                     min((end-start), cmd->argv[i].len));
  656.                 buf[min((end - start), cmd->argv[i].len - 1)] =
  657.                     '\0';
  658.                 cmd->argv[i].intval = (unative_t) buf;
  659.                 cmd->argv[i].vartype = ARG_TYPE_STRING;
  660.             } else if (!parse_int_arg(cmdline + start,
  661.                 end - start + 1, &cmd->argv[i].intval)) {
  662.                 cmd->argv[i].vartype = ARG_TYPE_INT;
  663.             } else {
  664.                 printf("Unrecognized variable argument.\n");
  665.                 error = 1;
  666.             }
  667.             break;
  668.         case ARG_TYPE_INVALID:
  669.         default:
  670.             printf("invalid argument type\n");
  671.             error = 1;
  672.             break;
  673.         }
  674.     }
  675.    
  676.     if (error) {
  677.         spinlock_unlock(&cmd->lock);
  678.         return NULL;
  679.     }
  680.    
  681.     start = end + 1;
  682.     if (parse_argument(cmdline, len, &start, &end)) {
  683.         printf("Too many arguments.\n");
  684.         spinlock_unlock(&cmd->lock);
  685.         return NULL;
  686.     }
  687.    
  688.     spinlock_unlock(&cmd->lock);
  689.     return cmd;
  690. }
  691.  
  692. /** Parse argument.
  693.  *
  694.  * Find start and end positions of command line argument.
  695.  *
  696.  * @param cmdline Command line as read from the input device.
  697.  * @param len Number of characters in cmdline.
  698.  * @param start On entry, 'start' contains pointer to the index
  699.  *        of first unprocessed character of cmdline.
  700.  *        On successful exit, it marks beginning of the next argument.
  701.  * @param end Undefined on entry. On exit, 'end' points to the last character
  702.  *        of the next argument.
  703.  *
  704.  * @return false on failure, true on success.
  705.  */
  706. bool parse_argument(char *cmdline, size_t len, index_t *start, index_t *end)
  707. {
  708.     index_t i;
  709.     bool found_start = false;
  710.    
  711.     ASSERT(start != NULL);
  712.     ASSERT(end != NULL);
  713.    
  714.     for (i = *start; i < len; i++) {
  715.         if (!found_start) {
  716.             if (isspace(cmdline[i]))
  717.                 (*start)++;
  718.             else
  719.                 found_start = true;
  720.         } else {
  721.             if (isspace(cmdline[i]))
  722.                 break;
  723.         }
  724.     }
  725.     *end = i - 1;
  726.  
  727.     return found_start;
  728. }
  729.  
  730. /** @}
  731.  */
  732.