From 0f1704a0f8c5fd2a4da6f530694bdd93a7ca3226 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ond=C5=99ej=20Poho=C5=99elsk=C3=BD?= <35430604+opohorel@users.noreply.github.com> Date: Mon, 8 Nov 2021 16:20:09 +0100 Subject: [PATCH] Add random within range '~' operator With the operator one can specify for a job a random time or date within a specified range for a field. The random value is generated when the crontab where the job is specified, is loaded. --- man/crontab.5 | 9 ++ src/entry.c | 262 ++++++++++++++++++++++++++++++++------------------ 2 files changed, 176 insertions(+), 95 deletions(-) diff --git a/man/crontab.5 b/man/crontab.5 index a011c89..ba8f0c3 100644 --- a/man/crontab.5 +++ b/man/crontab.5 @@ -199,6 +199,15 @@ hyphen. The specified range is inclusive. For example, 8-11 for an 'hours' entry specifies execution at hours 8, 9, 10, and 11. The first number must be less than or equal to the second one. .PP +Randomization of the execution time within a range can be used. +A random number within a range specified as two numbers separated with +a tilde is picked. The specified range is inclusive. +For example, 6~15 for a 'minutes' entry picks a random minute +within 6 to 15 range. The random number is picked when crontab file is parsed. +The first number must be less than or equal to the second one. You might omit +one or both of the numbers specifying the range. For example, ~ for a 'minutes' +entry picks a random minute within 0 to 59 range. +.PP Lists are allowed. A list is a set of numbers (or ranges) separated by commas. Examples: "1,2,5,9", "0-4,8-12". .PP diff --git a/src/entry.c b/src/entry.c index 92b55f5..9276f47 100644 --- a/src/entry.c +++ b/src/entry.c @@ -62,9 +62,22 @@ static const char *ecodes[] = { "out of memory" }; +typedef enum { + R_START, + R_AST, + R_STEP, + R_TERMS, + R_NUM1, + R_RANGE, + R_RANGE_NUM2, + R_RANDOM, + R_RANDOM_NUM2, + R_FINISH, +} range_state_t; + static int get_list(bitstr_t *, int, int, const char *[], int, FILE *), -get_range(bitstr_t *, int, int, const char *[], int, FILE *), -get_number(int *, int, const char *[], int, FILE *, const char *), +get_range(bitstr_t *, int, int, const char *[], FILE *), +get_number(int *, int, const char *[], FILE *), set_element(bitstr_t *, int, int, int); void free_entry(entry * e) { @@ -449,11 +462,14 @@ get_list(bitstr_t * bits, int low, int high, const char *names[], /* process all ranges */ done = FALSE; + /* unget ch to allow get_range() to process it properly + */ + unget_char(ch, file); while (!done) { - if (EOF == (ch = get_range(bits, low, high, names, ch, file))) + if (EOF == (ch = get_range(bits, low, high, names, file))) return (EOF); if (ch == ',') - ch = get_char(file); + continue; else done = TRUE; } @@ -468,137 +484,193 @@ get_list(bitstr_t * bits, int low, int high, const char *names[], return (ch); } +inline static int is_separator(int ch) { + switch (ch) { + case '\t': + case '\n': + case ' ': + case ',': + return 1; + default: + return 0; + } +} + + static int get_range(bitstr_t * bits, int low, int high, const char *names[], - int ch, FILE * file) { + FILE * file) { /* range = number | number "-" number [ "/" number ] + * | [number] "~" [number] */ + + int ch, i, num1, num2, num3; - int i, num1, num2, num3; + /* default value for step + */ + num3 = 1; + range_state_t state = R_START; + + while (state != R_FINISH && ((ch = get_char(file)) != EOF)) { + switch (state) { + case R_START: + if (ch == '*') { + num1 = low; + num2 = high; + state = R_AST; + break; + } + if (ch == '~') { + num1 = low; + state = R_RANDOM; + break; + } + unget_char(ch, file); + if (get_number(&num1, low, names, file) != EOF) { + state = R_NUM1; + break; + } + return (EOF); - Debug(DPARS | DEXT, ("get_range()...entering, exit won't show\n")); + case R_AST: + if (ch == '/') { + state = R_STEP; + break; + } + if (is_separator(ch)) { + state = R_FINISH; + break; + } + return (EOF); - if (ch == '*') { - /* '*' means "first-last" but can still be modified by /step - */ - num1 = low; - num2 = high; - ch = get_char(file); - if (ch == EOF) - return (EOF); - } - else { - ch = get_number(&num1, low, names, ch, file, ",- \t\n"); - if (ch == EOF) - return (EOF); + case R_STEP: + if (get_number(&num3, 0, PPC_NULL, file) != EOF) { + state = R_TERMS; + break; + } + return (EOF); - if (ch != '-') { - /* not a range, it's a single number. - */ - if (EOF == set_element(bits, low, high, num1)) { - unget_char(ch, file); + case R_TERMS: + if (is_separator(ch)) { + state = R_FINISH; + break; + } return (EOF); - } - return (ch); - } - else { - /* eat the dash - */ - ch = get_char(file); - if (ch == EOF) + + case R_NUM1: + if (ch == '-') { + state = R_RANGE; + break; + } + if (ch == '~') { + state = R_RANDOM; + break; + } + if (is_separator(ch)) { + num2 = num1; + state = R_FINISH; + break; + } return (EOF); - /* get the number following the dash - */ - ch = get_number(&num2, low, names, ch, file, "/, \t\n"); - if (ch == EOF || num1 > num2) + case R_RANGE: + if (get_number(&num2, low, names, file) != EOF) { + state = R_RANGE_NUM2; + break; + } return (EOF); - } - } - /* check for step size - */ - if (ch == '/') { - /* eat the slash - */ - ch = get_char(file); - if (ch == EOF) - return (EOF); + case R_RANGE_NUM2: + if (ch == '/') { + state = R_STEP; + break; + } + if (is_separator(ch)) { + state = R_FINISH; + break; + } + return (EOF); - /* get the step size -- note: we don't pass the - * names here, because the number is not an - * element id, it's a step size. 'low' is - * sent as a 0 since there is no offset either. - */ - ch = get_number(&num3, 0, PPC_NULL, ch, file, ", \t\n"); - if (ch == EOF || num3 == 0) - return (EOF); - } - else { - /* no step. default==1. - */ - num3 = 1; + case R_RANDOM: + if (is_separator(ch)) { + num2 = high; + state = R_FINISH; + } + else if (unget_char(ch, file), + get_number(&num2, low, names, file) != EOF) { + state = R_TERMS; + } + /* fail if couldn't find match on previous term + */ + else + return (EOF); + + /* if invalid random range was selected */ + if (num1 > num2) + return (EOF); + + /* select random number in range + */ + num1 = num2 = random() % (num2 - num1 + 1) + num1; + break; + + + default: + /* We should never get here + */ + return (EOF); + } } + if (state != R_FINISH || ch == EOF) + return (EOF); - /* range. set all elements from num1 to num2, stepping - * by num3. (the step is a downward-compatible extension - * proposed conceptually by bob@acornrc, syntactically - * designed then implemented by paul vixie). - */ for (i = num1; i <= num2; i += num3) if (EOF == set_element(bits, low, high, i)) { unget_char(ch, file); return (EOF); } - - return (ch); + return ch; } static int -get_number(int *numptr, int low, const char *names[], int ch, FILE * file, - const char *terms) { +get_number(int *numptr, int low, const char *names[], FILE * file) { char temp[MAX_TEMPSTR], *pc; - int len, i; + int len, i, ch; + char *endptr; pc = temp; len = 0; - /* first look for a number */ - while (isdigit((unsigned char) ch)) { + /* get all alnum characters available */ + while (isalnum((ch = get_char(file)))) { if (++len >= MAX_TEMPSTR) goto bad; *pc++ = (char)ch; - ch = get_char(file); } - *pc = '\0'; - if (len != 0) { - /* got a number, check for valid terminator */ - if (!strchr(terms, ch)) - goto bad; - *numptr = atoi(temp); - return (ch); + if (len == 0) + goto bad; + + unget_char(ch, file); + + /* try to get number */ + *numptr = (int) strtol(temp, &endptr, 10); + if (*endptr == '\0' && temp != endptr) { + /* We have a number */ + return 0; } /* no numbers, look for a string if we have any */ if (names) { - while (isalpha((unsigned char) ch)) { - if (++len >= MAX_TEMPSTR) - goto bad; - *pc++ = (char)ch; - ch = get_char(file); - } - *pc = '\0'; - if (len != 0 && strchr(terms, ch)) { - for (i = 0; names[i] != NULL; i++) { - Debug(DPARS | DEXT, - ("get_num, compare(%s,%s)\n", names[i], temp)); - if (!strcasecmp(names[i], temp)) { - *numptr = i + low; - return (ch); - } + for (i = 0; names[i] != NULL; i++) { + Debug(DPARS | DEXT, ("get_num, compare(%s,%s)\n", names[i], temp)); + if (strcasecmp(names[i], temp) == 0) { + *numptr = i + low; + return 0; } } + } else { + goto bad; } bad: -- 2.35.1