LibC: Implement getpw{nam,uid}_r
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@ -1,118 +1,142 @@
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#include <BAN/Assert.h>
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#include <ctype.h>
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#include <errno.h>
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#include <pwd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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static FILE* s_pwent_fp = nullptr;
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static passwd s_pwent_struct;
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static bool open_pwent()
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{
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if (s_pwent_fp)
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return true;
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s_pwent_fp = fopen("/etc/passwd", "r");
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return s_pwent_fp;
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}
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static void clear_pwent(passwd& passwd)
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{
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if (passwd.pw_name)
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free(passwd.pw_name);
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passwd.pw_name = nullptr;
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if (passwd.pw_dir)
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free(passwd.pw_dir);
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passwd.pw_dir = nullptr;
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if (passwd.pw_shell)
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free(passwd.pw_shell);
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passwd.pw_shell = nullptr;
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}
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static char* s_pwent_buffer = nullptr;
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static size_t s_pwent_buffer_size = 0;
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void endpwent(void)
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{
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if (s_pwent_fp)
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fclose(s_pwent_fp);
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s_pwent_fp = nullptr;
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if (s_pwent_buffer)
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free(s_pwent_buffer);
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s_pwent_buffer = nullptr;
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}
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void setpwent(void)
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{
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if (!s_pwent_fp)
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return;
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fclose(s_pwent_fp);
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s_pwent_fp = nullptr;
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clear_pwent(s_pwent_struct);
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fseek(s_pwent_fp, 0, SEEK_SET);
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}
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static int getpwent_impl(FILE* fp, struct passwd* pwd, char* buffer, size_t bufsize, struct passwd** result)
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{
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for (;;)
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{
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if (fgets(buffer, bufsize, fp) == nullptr)
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{
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if (ferror(fp))
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return errno;
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*result = nullptr;
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return 0;
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}
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const size_t line_len = strlen(buffer);
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if (line_len == 0)
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continue;
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if (buffer[line_len - 1] == '\n')
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buffer[line_len - 1] = '\0';
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else if (!feof(fp))
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return (errno = ERANGE);
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#define GET_STRING() ({ \
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ptr = strchr(ptr, ':'); \
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if (ptr == nullptr) \
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continue; \
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*ptr++ = '\0'; \
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})
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#define GET_INT() ({ \
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if (!isdigit(*ptr)) \
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continue; \
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long val = 0; \
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while (isdigit(*ptr)) \
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val = (val * 10) + (*ptr++ - '0'); \
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if (*ptr != ':') \
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continue; \
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*ptr++ = '\0'; \
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val; \
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})
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char* ptr = buffer;
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pwd->pw_name = ptr;
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GET_STRING();
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pwd->pw_passwd = ptr;
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GET_STRING();
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pwd->pw_uid = GET_INT();
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pwd->pw_gid = GET_INT();
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pwd->pw_gecos = ptr;
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GET_STRING();
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pwd->pw_dir = ptr;
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GET_STRING();
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pwd->pw_shell = ptr;
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*result = pwd;
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return 0;
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}
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}
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struct passwd* getpwent(void)
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{
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if (!s_pwent_fp)
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if (!open_pwent())
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return nullptr;
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clear_pwent(s_pwent_struct);
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static char buffer[4096];
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if (!fgets(buffer, sizeof(buffer), s_pwent_fp))
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return nullptr;
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size_t buffer_len = strlen(buffer);
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ASSERT(buffer[buffer_len - 1] == '\n');
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buffer[buffer_len - 1] = '\0';
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buffer_len--;
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const char* ptr = buffer;
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for (int i = 0; i < 7; i++)
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if (s_pwent_fp == nullptr)
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{
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char* end = strchr(ptr, ':');
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ASSERT((i < 6) ? end != nullptr : end == nullptr);
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if (!end)
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end = buffer + buffer_len;
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*end = '\0';
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const size_t field_len = end - ptr;
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switch (i)
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{
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case 0:
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s_pwent_struct.pw_name = strndup(ptr, field_len + 1);
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if (!s_pwent_struct.pw_name)
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return nullptr;
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break;
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case 1:
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s_pwent_struct.pw_passwd = strndup(ptr, field_len + 1);
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if (!s_pwent_struct.pw_passwd)
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return nullptr;
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break;
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case 2:
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ASSERT(1 <= field_len && field_len <= 9);
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for (size_t j = 0; j < field_len; j++)
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ASSERT(isdigit(ptr[j]));
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s_pwent_struct.pw_uid = atoi(ptr);
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break;
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case 3:
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ASSERT(1 <= field_len && field_len <= 9);
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for (size_t j = 0; j < field_len; j++)
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ASSERT(isdigit(ptr[j]));
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s_pwent_struct.pw_gid = atoi(ptr);
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break;
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case 4:
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s_pwent_struct.pw_gecos = strndup(ptr, field_len + 1);
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if (!s_pwent_struct.pw_gecos)
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return nullptr;
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break;
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case 5:
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s_pwent_struct.pw_dir = strndup(ptr, field_len + 1);
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if (!s_pwent_struct.pw_dir)
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return nullptr;
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break;
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case 6:
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s_pwent_struct.pw_shell = strndup(ptr, field_len + 1);
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if (!s_pwent_struct.pw_shell)
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return nullptr;
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break;
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}
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ptr = end + 1;
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s_pwent_fp = fopen("/etc/passwd", "r");
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if (s_pwent_fp == nullptr)
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return nullptr;
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}
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return &s_pwent_struct;
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if (s_pwent_buffer == nullptr)
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{
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long size = sysconf(_SC_GETPW_R_SIZE_MAX);
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if (size == -1)
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size = 512;
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s_pwent_buffer = static_cast<char*>(malloc(size));
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if (s_pwent_buffer == nullptr)
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return nullptr;
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s_pwent_buffer_size = size;
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}
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const off_t old_offset = ftello(s_pwent_fp);
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passwd* result;
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for (;;)
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{
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const int error = getpwent_impl(s_pwent_fp, &s_pwent_struct, s_pwent_buffer, s_pwent_buffer_size, &result);
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if (error == 0)
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break;
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fseeko(s_pwent_fp, old_offset, SEEK_SET);
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if (error != ERANGE)
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return nullptr;
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const size_t new_size = s_pwent_buffer_size * 2;
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char* new_buffer = static_cast<char*>(realloc(s_pwent_buffer, new_size));
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if (new_buffer == nullptr)
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return nullptr;
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s_pwent_buffer = new_buffer;
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s_pwent_buffer_size = new_size;
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}
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return result;
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}
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struct passwd* getpwnam(const char* name)
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@ -135,9 +159,44 @@ struct passwd* getpwuid(uid_t uid)
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return nullptr;
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}
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void setpwent(void)
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int getpwuid_r(uid_t uid, struct passwd* pwd, char* buffer, size_t bufsize, struct passwd** result)
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{
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if (!s_pwent_fp)
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return;
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fseek(s_pwent_fp, 0, SEEK_SET);
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FILE* fp = fopen("/etc/passwd", "r");
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if (fp == nullptr)
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return errno;
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int ret = 0;
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for (;;)
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{
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if ((ret = getpwent_impl(fp, pwd, buffer, bufsize, result)))
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break;
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if (*result == nullptr)
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break;
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if (pwd->pw_uid == uid)
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break;
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}
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fclose(fp);
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return ret;
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}
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int getpwnam_r(const char* name, struct passwd* pwd, char* buffer, size_t bufsize, struct passwd** result)
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{
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FILE* fp = fopen("/etc/passwd", "r");
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if (fp == nullptr)
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return errno;
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int ret = 0;
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for (;;)
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{
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if ((ret = getpwent_impl(fp, pwd, buffer, bufsize, result)))
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break;
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if (*result == nullptr)
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break;
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if (strcmp(pwd->pw_name, name) == 0)
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break;
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}
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fclose(fp);
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return ret;
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}
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