附加向量

1 附加向量

1.1 附加向量

Auxiliary vector是一种机制，内核的ELF binary loader使用附加向量在程序执行时传递某些信息到用户空间。

 #include <sys/auxv.h>

unsigned long getauxval(unsigned long type);

 

sys/auxv.h

#define AT_NULL         0               /* End of vector */ #define AT_IGNORE       1               /* Entry should be ignored */ #define AT_EXECFD       2               /* File descriptor of program */ #define AT_PHDR         3               /* Program headers for program */ #define AT_PHENT        4               /* Size of program header entry */ #define AT_PHNUM        5               /* Number of program headers */ #define AT_PAGESZ       6               /* System page size */ #define AT_BASE         7               /* Base address of interpreter */ #define AT_FLAGS        8               /* Flags */ #define AT_ENTRY        9               /* Entry point of program */ #define AT_NOTELF       10              /* Program is not ELF */ #define AT_UID          11              /* Real uid */ #define AT_EUID         12              /* Effective uid */ #define AT_GID          13              /* Real gid */ #define AT_EGID         14              /* Effective gid */ #define AT_CLKTCK       17              /* Frequency of times() */   /* Some more special a_type values describing the hardware.  */ #define AT_PLATFORM     15              /* String identifying platform.  */ #define AT_HWCAP        16              /* Machine-dependent hints about                                            processor capabilities.  */   /* This entry gives some information about the FPU initialization    performed by the kernel.  */ #define AT_FPUCW        18              /* Used FPU control word.  */   /* Cache block sizes.  */ #define AT_DCACHEBSIZE  19              /* Data cache block size.  */ #define AT_ICACHEBSIZE  20              /* Instruction cache block size.  */ #define AT_UCACHEBSIZE  21              /* Unified cache block size.  */