How to find definition of structure when reading c program on linux?

Question

I am reading source code of xl2tpd, and face lots of problems when reading this code. For example I cannot find where the structure lac is defined. How do I find the definition of this structure?

I have used ctags and vim to read this code, but failed to find the structure. I googled and could not find the structure. Is there any method that can make the code reading process more comfortable? That is, I can jump to definition of most variables, functions and structures?

Answer 1

try cscope with vim. follow steps below -
1) run cscope -R in xl2tpd directory . it will create file cscope.out
2) open file with vim where structure lac is used
3) use :cs f g <lac> . now it will show the files where lac is defined .
4) choose file.h. it contain the definition .
if you are perticulerly interested in definition of struct lac it is below -

struct lac
{
    struct lac *next;
    struct host *lns;           /* LNS's we can connect to */
    struct schedule_entry *rsched;
    int tun_rws;                /* Receive window size (tunnel) */
    int call_rws;               /* Call rws */
    int rxspeed;                /* Tunnel rx speed */
    int txspeed;                /* Tunnel tx speed */
    int active;                 /* Is this connection in active use? */
    int hbit;                   /* Permit hidden AVP's? */
    int lbit;                   /* Use the length field? */
    int challenge;              /* Challenge authenticate the peer? */
    unsigned int localaddr;     /* Local IP address */    
    unsigned int remoteaddr;    /* Force remote address to this */
    char authname[STRLEN];      /* Who we authenticate as */
    char password[STRLEN];      /* Password to authenticate with */
    char peername[STRLEN];      /* Force peer name to this */
    char hostname[STRLEN];      /* Hostname to report */
    char entname[STRLEN];       /* Name of this entry */
    int authpeer;               /* Authenticate our peer? */
    int authself;               /* Authenticate ourselves? */
    int pap_require;            /* Require PAP auth for PPP */
    int chap_require;           /* Require CHAP auth for PPP */
    int pap_refuse;             /* Refuse PAP authentication for us */
    int chap_refuse;            /* Refuse CHAP authentication for us */
    int idle;                   /* Idle timeout in seconds */
    int autodial;               /* Try to dial immediately? */
    int defaultroute;           /* Use as default route? */
    int redial;                 /* Redial if disconnected */
    int rmax;                   /* Maximum # of consecutive redials */
    int rtries;                 /* # of tries so far */
    int rtimeout;               /* Redial every this many # of seconds */
    char pppoptfile[STRLEN];    /* File containing PPP options */
    int debug;
    struct tunnel *t;           /* Our tunnel */
    struct call *c;             /* Our call */
};

Answer 2

When going through third-party code, there are a few tools that I have found invaluable:

• Source Navigator

• lxr

• ctags

• and, of course, the oldest and greatest of all: grep

I believe that the Eclipse CDT also allows you to quickly find the definition of any variable you are looking at, but I have not actually used it - I prefer using console programs for my actual C coding.

None of those are vim-based, although at least ctags can be used via vim or emacs. Nevertheless, they can be very useful when exploring a new codebase that you know nothing about...