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config_parser: implement <number>s, proper error handling
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@stapelberg
stapelberg committed Oct 8, 2012
1 parent a635945 commit 6f9e6c1
Showing 1 changed file with 203 additions and 51 deletions.
254 changes: 203 additions & 51 deletions src/config_parser.c
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Expand Up @@ -10,6 +10,17 @@
*
* See also src/commands_parser.c for rationale on why we use a custom parser.
*
* This parser works VERY MUCH like src/commands_parser.c, so read that first.
* The differences are:
*
* 1. config_parser supports the 'number' token type (in addition to 'word' and
* 'string'). Numbers are referred to using &num (like $str).
*
* 2. Criteria are not executed immediately, they are just stored.
*
* 3. config_parser recognizes \n and \r as 'end' token, while commands_parser
* ignores them.
*
*/
#include <stdio.h>
#include <stdlib.h>
Expand Down Expand Up @@ -59,7 +70,14 @@ typedef struct tokenptr {
struct stack_entry {
/* Just a pointer, not dynamically allocated. */
const char *identifier;
char *str;
enum {
STACK_STR = 0,
STACK_LONG = 1,
} type;
union {
char *str;
long num;
} val;
};

/* 10 entries should be enough for everybody. */
Expand All @@ -73,16 +91,17 @@ static struct stack_entry stack[10];
static void push_string(const char *identifier, char *str) {
for (int c = 0; c < 10; c++) {
if (stack[c].identifier != NULL &&
strcmp(stack[c].identifier, identifier) != 0)
strcmp(stack[c].identifier, identifier) != 0)
continue;
if (stack[c].identifier == NULL) {
/* Found a free slot, let’s store it here. */
stack[c].identifier = identifier;
stack[c].str = str;
} else {
/* Append the value. */
sasprintf(&(stack[c].str), "%s,%s", stack[c].str, str);
}
if (stack[c].identifier == NULL) {
/* Found a free slot, let’s store it here. */
stack[c].identifier = identifier;
stack[c].val.str = str;
stack[c].type = STACK_STR;
} else {
/* Append the value. */
sasprintf(&(stack[c].val.str), "%s,%s", stack[c].val.str, str);
}
return;
}

Expand All @@ -95,24 +114,54 @@ static void push_string(const char *identifier, char *str) {
exit(1);
}

// XXX: ideally, this would be const char. need to check if that works with all
// called functions.
static char *get_string(const char *identifier) {
static void push_long(const char *identifier, long num) {
for (int c = 0; c < 10; c++) {
if (stack[c].identifier != NULL)
continue;
/* Found a free slot, let’s store it here. */
stack[c].identifier = identifier;
stack[c].val.num = num;
stack[c].type = STACK_LONG;
return;
}

/* When we arrive here, the stack is full. This should not happen and
* means there’s either a bug in this parser or the specification
* contains a command with more than 10 identified tokens. */
fprintf(stderr, "BUG: commands_parser stack full. This means either a bug "
"in the code, or a new command which contains more than "
"10 identified tokens.\n");
exit(1);

}

static const char *get_string(const char *identifier) {
for (int c = 0; c < 10; c++) {
if (stack[c].identifier == NULL)
break;
if (strcmp(identifier, stack[c].identifier) == 0)
return stack[c].str;
return stack[c].val.str;
}
return NULL;
}

static const long get_long(const char *identifier) {
for (int c = 0; c < 10; c++) {
if (stack[c].identifier == NULL)
break;
if (strcmp(identifier, stack[c].identifier) == 0)
return stack[c].val.num;
}
return 0;
}

static void clear_stack(void) {
for (int c = 0; c < 10; c++) {
if (stack[c].str != NULL)
free(stack[c].str);
if (stack[c].type == STACK_STR && stack[c].val.str != NULL)
free(stack[c].val.str);
stack[c].identifier = NULL;
stack[c].str = NULL;
stack[c].val.str = NULL;
stack[c].val.num = 0;
}
}

Expand Down Expand Up @@ -168,11 +217,9 @@ static void clear_criteria(void *unused_criteria) {
******************************************************************************/

static cmdp_state state;
#ifndef TEST_PARSER
static Match current_match;
#endif
static struct CommandResult subcommand_output;
static struct CommandResult command_output;
static struct ConfigResult subcommand_output;
static struct ConfigResult command_output;

#include "GENERATED_config_call.h"

Expand All @@ -182,12 +229,7 @@ static void next_state(const cmdp_token *token) {
//printf("next_state = %d\n", token->next_state);
if (token->next_state == __CALL) {
subcommand_output.json_gen = command_output.json_gen;
subcommand_output.needs_tree_render = false;
GENERATED_call(token->extra.call_identifier, &subcommand_output);
/* If any subcommand requires a tree_render(), we need to make the
* whole parser result request a tree_render(). */
if (subcommand_output.needs_tree_render)
command_output.needs_tree_render = true;
clear_stack();
return;
}
Expand All @@ -198,8 +240,49 @@ static void next_state(const cmdp_token *token) {
}
}

struct CommandResult *parse_config(const char *input) {
DLOG("COMMAND: *%s*\n", input);
/*
* Returns a pointer to the start of the line (one byte after the previous \r,
* \n) or the start of the input, if this is the first line.
*
*/
static const char *start_of_line(const char *walk, const char *beginning) {
while (*walk != '\n' && *walk != '\r' && walk >= beginning) {
walk--;
}

return walk + 1;
}

/*
* Copies the line and terminates it at the next \n, if any.
*
* The caller has to free() the result.
*
*/
static char *single_line(const char *start) {
char *result = sstrdup(start);
char *end = strchr(result, '\n');
if (end != NULL)
*end = '\0';
return result;
}

struct ConfigResult *parse_config(const char *input, struct context *context) {
/* Dump the entire config file into the debug log. We cannot just use
* DLOG("%s", input); because one log message must not exceed 4 KiB. */
const char *dumpwalk = input;
int linecnt = 1;
while (*dumpwalk != '\0') {
char *next_nl = strchr(dumpwalk, '\n');
if (next_nl != NULL) {
DLOG("CONFIG(line %3d): %.*s\n", linecnt, (next_nl - dumpwalk), dumpwalk);
dumpwalk = next_nl + 1;
} else {
DLOG("CONFIG(line %3d): %s\n", linecnt, dumpwalk);
break;
}
linecnt++;
}
state = INITIAL;

/* A YAJL JSON generator used for formatting replies. */
Expand All @@ -210,25 +293,25 @@ struct CommandResult *parse_config(const char *input) {
#endif

y(array_open);
command_output.needs_tree_render = false;

const char *walk = input;
const size_t len = strlen(input);
int c;
const cmdp_token *token;
bool token_handled;
linecnt = 1;

// TODO: make this testable
#ifndef TEST_PARSER
cmd_criteria_init(&current_match, &subcommand_output);
cfg_criteria_init(&current_match, &subcommand_output, INITIAL);
#endif

/* The "<=" operator is intentional: We also handle the terminating 0-byte
* explicitly by looking for an 'end' token. */
while ((walk - input) <= len) {
/* skip whitespace and newlines before every token */
while ((*walk == ' ' || *walk == '\t' ||
*walk == '\r' || *walk == '\n') && *walk != '\0')
/* Skip whitespace before every token, newlines are relevant since they
* separate configuration directives. */
while ((*walk == ' ' || *walk == '\t') && *walk != '\0')
walk++;

//printf("remaining input: %s\n", walk);
Expand All @@ -251,6 +334,29 @@ struct CommandResult *parse_config(const char *input) {
continue;
}

if (strcmp(token->name, "number") == 0) {
/* Handle numbers. We only accept decimal numbers for now. */
char *end = NULL;
errno = 0;
long int num = strtol(walk, &end, 10);
if ((errno == ERANGE && (num == LONG_MIN || num == LONG_MAX)) ||
(errno != 0 && num == 0))
continue;

/* No valid numbers found */
if (end == walk)
continue;

if (token->identifier != NULL)
push_long(token->identifier, num);

/* Set walk to the first non-number character */
walk = end;
next_state(token);
token_handled = true;
break;
}

if (strcmp(token->name, "string") == 0 ||
strcmp(token->name, "word") == 0) {
const char *beginning = walk;
Expand All @@ -262,13 +368,7 @@ struct CommandResult *parse_config(const char *input) {
walk++;
} else {
if (token->name[0] == 's') {
/* For a string (starting with 's'), the delimiters are
* comma (,) and semicolon (;) which introduce a new
* operation or command, respectively. Also, newlines
* end a command. */
while (*walk != ';' && *walk != ',' &&
*walk != '\0' && *walk != '\r' &&
*walk != '\n')
while (*walk != '\0' && *walk != '\r' && *walk != '\n')
walk++;
} else {
/* For a word, the delimiters are white space (' ' or
Expand Down Expand Up @@ -308,7 +408,8 @@ struct CommandResult *parse_config(const char *input) {
}

if (strcmp(token->name, "end") == 0) {
if (*walk == '\0' || *walk == ',' || *walk == ';') {
//printf("checking for end: *%s*\n", walk);
if (*walk == '\0' || *walk == '\n' || *walk == '\r') {
next_state(token);
token_handled = true;
/* To make sure we start with an appropriate matching
Expand All @@ -317,9 +418,9 @@ struct CommandResult *parse_config(const char *input) {
* every command. */
// TODO: make this testable
#ifndef TEST_PARSER
if (*walk == '\0' || *walk == ';')
cmd_criteria_init(&current_match, &subcommand_output);
cfg_criteria_init(&current_match, &subcommand_output, INITIAL);
#endif
linecnt++;
walk++;
break;
}
Expand Down Expand Up @@ -366,16 +467,52 @@ struct CommandResult *parse_config(const char *input) {
possible_tokens);
free(possible_tokens);


/* Go back to the beginning of the line */
const char *error_line = start_of_line(walk, input);

/* Contains the same amount of characters as 'input' has, but with
* the unparseable part highlighted using ^ characters. */
char *position = smalloc(len + 1);
for (const char *copywalk = input; *copywalk != '\0'; copywalk++)
position[(copywalk - input)] = (copywalk >= walk ? '^' : ' ');
position[len] = '\0';
char *position = scalloc(strlen(error_line) + 1);
const char *copywalk;
for (copywalk = error_line;
*copywalk != '\n' && *copywalk != '\r' && *copywalk != '\0';
copywalk++)
position[(copywalk - error_line)] = (copywalk >= walk ? '^' : (*copywalk == '\t' ? '\t' : ' '));
position[(copywalk - error_line)] = '\0';

ELOG("CONFIG: %s\n", errormessage);
ELOG("CONFIG: (in file %s)\n", context->filename);
char *error_copy = single_line(error_line);

/* Print context lines *before* the error, if any. */
if (linecnt > 1) {
const char *context_p1_start = start_of_line(error_line-2, input);
char *context_p1_line = single_line(context_p1_start);
if (linecnt > 2) {
const char *context_p2_start = start_of_line(context_p1_start-2, input);
char *context_p2_line = single_line(context_p2_start);
ELOG("CONFIG: Line %3d: %s\n", linecnt - 2, context_p2_line);
free(context_p2_line);
}
ELOG("CONFIG: Line %3d: %s\n", linecnt - 1, context_p1_line);
free(context_p1_line);
}
ELOG("CONFIG: Line %3d: %s\n", linecnt, error_copy);
ELOG("CONFIG: %s\n", position);
free(error_copy);
/* Print context lines *after* the error, if any. */
for (int i = 0; i < 2; i++) {
char *error_line_end = strchr(error_line, '\n');
if (error_line_end != NULL && *(error_line_end + 1) != '\0') {
error_line = error_line_end + 1;
error_copy = single_line(error_line);
ELOG("CONFIG: Line %3d: %s\n", linecnt + i + 1, error_copy);
free(error_copy);
}
}

ELOG("%s\n", errormessage);
ELOG("Your command: %s\n", input);
ELOG(" %s\n", position);
context->has_errors = true;

/* Format this error message as a JSON reply. */
y(map_open);
Expand Down Expand Up @@ -436,11 +573,26 @@ void errorlog(char *fmt, ...) {
va_end(args);
}

static int criteria_next_state;

void cfg_criteria_init(I3_CFG, int _state) {
criteria_next_state = _state;
}

void cfg_criteria_add(I3_CFG, const char *ctype, const char *cvalue) {
}

void cfg_criteria_pop_state(I3_CFG) {
result->next_state = criteria_next_state;
}

int main(int argc, char *argv[]) {
if (argc < 2) {
fprintf(stderr, "Syntax: %s <command>\n", argv[0]);
return 1;
}
parse_config(argv[1]);
struct context context;
context.filename = "<stdin>";
parse_config(argv[1], &context);
}
#endif

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