这些代码原来是别人委托我开发，用来控制JVM的CPU使用率的， 后来因为种种原因，之开发到一半，所以现在写到博客里了。。。。
process.h
1 #ifndef PROCESS_H_INCLUDED 2 #define PROCESS_H_INCLUDED 3 char *basename(const char *path); 4 int get_pid_by_name(const char* process_name, pid_t pid_list[], int list_size); 5 int is_process_exist(const char* process_name); 6 #endif // PROCESS_H_INCLUDED
process.c
1 #include <stdio.h> 2 #include <stdlib.h> 3 #include <unistd.h> 4 #include <string.h> 5 #include <sys/types.h> 6 #include <dirent.h> 7 #include <ctype.h> 8 #include <errno.h> 9 char *basename(const char *path) 10 { 11 register const char *s; 12 register const char *p; 13 14 p = s = path; 15 16 while (*s) { 17 if (*s++ == '/') { 18 p = s; 19 } 20 } 21 22 return (char *) p; 23 } 24 25 /* 根据进程名称获取PID, 比较 base name of pid_name 26 * pid_list: 获取PID列表 27 * list_size: 获取PID列表长度 28 * RETURN值说明: 29 * < 0: 30 * >=0: 发现多少PID, pid_list 将保存已发现的PID 31 */ 32 int get_pid_by_name(const char* process_name, pid_t pid_list[], int list_size) 33 { 34 #define MAX_BUF_SIZE 256 35 36 DIR *dir; 37 struct dirent *next; 38 int count=0; 39 pid_t pid; 40 FILE *fp; 41 char *base_pname = NULL; 42 char *base_fname = NULL; 43 char cmdline[MAX_BUF_SIZE]; 44 char path[MAX_BUF_SIZE]; 45 46 if(process_name == NULL || pid_list == NULL) 47 return -EINVAL; 48 49 base_pname = basename(process_name); 50 if(strlen(base_pname) <= 0) 51 return -EINVAL; 52 53 dir = opendir("/proc"); 54 if (!dir) 55 { 56 return -EIO; 57 } 58 while ((next = readdir(dir)) != NULL) { 59 /* skip non-number */ 60 if (!isdigit(*next->d_name)) 61 continue; 62 63 pid = strtol(next->d_name, NULL, 0); 64 sprintf(path, "/proc/%u/cmdline", pid); 65 fp = fopen(path, "r"); 66 if(fp == NULL) 67 continue; 68 69 memset(cmdline, 0, sizeof(cmdline)); 70 if(fread(cmdline, MAX_BUF_SIZE - 1, 1, fp) < 0){ 71 fclose(fp); 72 continue; 73 } 74 fclose(fp); 75 base_fname = basename(cmdline); 76 77 if (strcmp(base_fname, base_pname) == 0 ) 78 { 79 if(count >= list_size){ 80 break; 81 }else{ 82 pid_list[count] = pid; 83 count++; 84 } 85 } 86 } 87 closedir(dir) ; 88 return count; 89 } 90 91 /* 如果进程已经存在, return true */ 92 int is_process_exist(const char* process_name) 93 { 94 pid_t pid; 95 96 return (get_pid_by_name(process_name, &pid, 1) > 0); 97 }
main.c
#include <stdlib.h> #include <stdio.h> #include "process.h" #define MAX_PID_NUM 32 int main(int argc, char* argv[]) { char* process; int ret = 0; int n; pid_t pid[MAX_PID_NUM]; if(argc < 2) process = argv[0]; else process = argv[1]; ret = get_pid_by_name(process, pid, MAX_PID_NUM); printf("process '%s' is existed? (%d): %c\n", process, ret, (ret > 0)?'y':'n'); for(n=0;n<ret;n++){ printf("%u\n", pid[n]); } return ret; }
Makefile:
1 PROG=check_process 2 OBJS=process.o main.o 3 #CFLAGS = -g -ggdb 4 5 all:$(PROG) 6 7 check_process:$(OBJS) 8 $(CC) -o $@ $^ $(LDFLAGS) 9 10 %.o:%.c 11 $(CC) -c -o $@ $(CFLAGS) $< 12 13 clean: 14 rm -rf $(PROG) *.o