Question

我正在尝试使用下面的代码解析uevent，但我认为我的正则表达式不正确导致regcomp函数失败。

有人可以帮忙吗？我正在尝试做this之类的事情。

#include <stdio.h>
#include <string.h>
#include <regex.h>

int main ()
{
  char * source = "change@/devices/soc/799999.i2c/i2c-3/3-0015/power_supply/battery";
  char * regexString = "(?<action>[a-zA-Z]+)@\\/(?<dev_path>.*)\\/(?<subsystem>[a-zA-z]+)\\/(?<name>[a-zA-z]+)";
  size_t maxGroups = 4;

  regex_t regexCompiled;
  regmatch_t groupArray[maxGroups];

  if (regcomp(&regexCompiled, regexString, REG_EXTENDED))
    {
      printf("Could not compile regular expression.\n");
      return 1;
    };
  regfree(&regexCompiled);

  return 0; 
}

我收到“无法编译正则表达式。”。这意味着regcomp无法识别正则表达式。

Answer 1

当我使用代码报告错误时：

#include <stdio.h>
#include <string.h>
#include <regex.h>

int main(void)
{
  //char * source = "change@/devices/soc/799999.i2c/i2c-3/3-0015/power_supply/battery";
  char * regexString = "(?<action>[a-zA-Z]+)@\\/(?<dev_path>.*)\\/(?<subsystem>[a-zA-z]+)\\/(?<name>[a-zA-z]+)";
  //size_t maxGroups = 4;

  regex_t regexCompiled;
  //regmatch_t groupArray[maxGroups];

  int rc;
  if ((rc = regcomp(&regexCompiled, regexString, REG_EXTENDED)) != 0)
    {
      char buffer[1024];
      regerror(rc, &regexCompiled, buffer, sizeof(buffer));
      printf("Could not compile regular expression (%d: %s).\n", rc, buffer);
      return 1;
    }
  regfree(&regexCompiled);

  return 0; 
}

我得到了输出：

Could not compile regular expression (13: repetition-operator operand invalid).

问题在于您使用的符号(?：

"(?<action>[a-zA-Z]+)@\\/(?<dev_path>.*)\\/(?<subsystem>[a-zA-z]+)\\/(?<name>[a-zA-z]+)"

该表示法适用于PCRE而非POSIX。并且PCRE在?之后使用(正是因为它在其他正则表达式系统（例如POSIX）中无效。

因此，如果您想使用PCRE正则表达式，请安装并使用PCRE库。

否则，您需要使用：

"([a-zA-Z]+)@\\/(.*)\\/([a-zA-z]+)\\/([a-zA-z]+)"

有了这个，并注意到你需要一个regmatch_t来匹配整个字符串以及4个捕获的组（总共5个捕获），你可以写：

#include <stdio.h>
#include <string.h>
#include <regex.h>

int main(void)
{
    char *source = "change@/devices/soc/799999.i2c/i2c-3/3-0015/power_supply/battery";
    // char * regexString = "(?<action>[a-zA-Z]+)@\\/(?<dev_path>.*)\\/(?<subsystem>[a-zA-z]+)\\/(?<name>[a-zA-z]+)";
    size_t maxGroups = 5;
    char *regexString =  "([a-zA-Z]+)@\\/(.*)\\/([a-zA-z]+)\\/([a-zA-z]+)";

    regex_t regexCompiled;
    regmatch_t groupArray[maxGroups];

    int rc;
    if ((rc = regcomp(&regexCompiled, regexString, REG_EXTENDED)) != 0)
    {
        char buffer[1024];
        regerror(rc, &regexCompiled, buffer, sizeof(buffer));
        printf("Could not compile regular expression (%d: %s).\n", rc, buffer);
        return 1;
    }
    if ((rc = regexec(&regexCompiled, source, maxGroups, groupArray, 0)) != 0)
    {
        char buffer[1024];
        regerror(rc, &regexCompiled, buffer, sizeof(buffer));
        printf("Could not execute regular expression (%d: %s).\n", rc, buffer);
        return 1;
    }

    printf("Match successful:\n");
    for (size_t i = 0; i < maxGroups; i++)
    {
        int so = groupArray[i].rm_so;
        int eo = groupArray[i].rm_eo;
        printf("%zu: %d..%d [%.*s]\n", i, so, eo, eo - so, &source[so]);
    }

    regfree(&regexCompiled);

    return 0;
}

，输出为：

Match successful:
0: 0..64 [change@/devices/soc/799999.i2c/i2c-3/3-0015/power_supply/battery]
1: 0..6 [change]
2: 8..43 [devices/soc/799999.i2c/i2c-3/3-0015]
3: 44..56 [power_supply]
4: 57..64 [battery]

posix正则表达式，用于解析uevent导致错误

1 个答案: